Most reliable enduro build

IMO,
Frame is highly subjective as theres so many fanboys/girls.
Probably a Norco sight with the Cascade link and Increased stroke.(alloy.. its builk like an absolute tank)

hubs... Anything silent with less engagement... up to dtswiss 350/ln 36T is good.

spokes... dt swiss

Rims... Again highly subjective from People running way to low pressure But  You'd be silly not to Choose Reserve or like the dt471
(Theres wheels like Nukeproof hzn v2 and spank 359's that are waaay underrated but will easily Take punishment)

tires... Take your pick from the top Proven MTB brands, maxxis/schwable/conti

brakes... oh here we go... TRP or hope tech 4.

discs/rotors... TRP... 

pads, Probably shimano. just proven.

Shock - Super deluxe Ultimate, wicked shock thats cost friendly aswell.

Fork... all are pretty good...pick your poison they all work - if i had to choose for a multi day enduro, probably a fox 36/38 that was built by someone other than fox.

handlebars... ONEUP every day.

headset, Many will say chris king but nothing wrong with a quality Cane creak one.

dropper... probably Fox - yeah oneup/pnw etc are good but they all rattle and have stupid play in then...

grips... all are good and personal pref... Not worth answering.

saddle... see grips.

Derailleur... Sram xx1... Shimano's just break at the Plastic bit on the outside if you even look at them funny.

Shifter... GX/SLX, People like the multi XT but i found the XT shifter can crap out and its a bit harder to push than SLX.

cranks... any but hollowtech is good.

BB, Hambini... Dont talk sh1t if youve never tried one, they are seriously nice and built for proper abuse.

chain... xx1.

chainring, All are OK - except absolutecrap... they are crap.

Pedals. subjective but Mallet DH/Enduro - flats, oneup alloy or dagga's.

Rest are just basic stuff.

Having seen Astons experience with his Norco, unsure if I would suggest them in the context of most reliable.

But absolutely agree on wheels, headset and shifting (running GX on enduro and dh, no issues so far + easy and cheap to source).

Getting a little fancier framewise, have a look at Nicolai. I just picked up a Nicolai G19 from one of their sponsored riders. Was a spare frame sitting on the shelf for two years as the first frame didn't break (Fest jumps, etc. included). Having an alloy Kona Process in comparison the G19 feels bombproof and high quality.

Newmen wheels are really good in terms of dent resistance. I don't think that the hubs were any better than any of the other comparable brands out there, but the rims were really stout. I rode them for a couple of seasons and were the only alloy rims that have never dented. They're not necessarily the most convenient to get if you live in the US, but they're legit alloy rims. 

Most of the stuff is subjective, but I prefer SRAM drivetrain to Shimano stuff. Hard to go wrong with GX stuff, other than the clutch seems to wear out regardless of how bike is maintained. 

Second the comment regarding a Nicolai frame. The difference a stout frame makes across a variety of factors was one of the bigger surprises for me after I spent some real time on the G1. All the bolts, including the rear axle, don't work themselves loose and the bolt heads are properly sized for the torque specs. The shock isn't stressed, everything is very well sealed and packed with grease from the factory. The spherical eyelet bearings in the shock far outlast bushings. The list goes on, but the overall point is that the frame has cascading durability implications.

most reliable shock is SuperDeluxe R

but yes the Ultimate is way nicer.

Cranks- either those titanium ones or anything forged 7xxx aluminum- pedal threads are going to be 2x harder to strip out vs 6xxx aluminum.

I don’t post post much here but this is a subject I have a bit of experience with. For the past 3 years in a row I climbed over 750,000 feet each year and about 3000 miles each year so I have put a fair bit of hurt on components and bikes. I live in a steep area and ride all dh type trails.

Frame: Santa Cruz Megatower V1, this frame has been absolutely bulletproof, one bearing change each year and that’s been it, it did eventually crack at the end of last year but Santa Cruz replaced it no issue

Rear shock: I used a rockshox super deluxe air for the first season, they are a great wee shock but do require a bit of servicing both on the air can and the damper oil itself would be foamed up after 3/4 months of riding. For two years I used an ohlins coil and it was incredible, simple to set up and not a single issue.

Forks: during the 3 years I had 3 sets of rockshox lyriks, I generally like the old 2.1 charger for easy servicing and decent performance but I had various problems with upper leg anodising wearing off and creaks at the crown. I’m currently on the new Zeb for about 8 months and they have been great thus far.

Wheels: newmen rims are by far the best rim I’ve used, I also have newmen hubs and they are probably slightly better than a dt Swiss 350 and much better than a hope pro 4. Build those newmen rims with sapim d lights, use the mg rim washer with sapim polyax style nipples and I can get nearly a full season out of a rear and I have been running the same front newmen rim and hub since July 2018 (albeit the hub has seen plenty of new bearings in that time) 

Brakes: I ran the same set of avid code RSC for the whole 3 years on that bike, I only bled them twice, people talk crap about sram brakes but I had no issues other than the common bite adjuster seizing but that was easily fixed with a lever strip down, the problem with them is the little detent ball getting rusty and stopping the wheel rotating so I took them out and they worked fine. I went through a mountain of brake pads but srams own sintered where hard to beat. 
 

Seatpost: good old oneup dropper, the original one got replaced under warranty and every since then general servicing has kept it golden.

Drivetrain: SRAM GX. I could get a full year out of the cassette before the top cog started slipping, xo chains were great, GX rubbish. GX rear derailleurs where in a constant warranty rotation every 4 months or so the clutch would die but sram usually replaced them.

Tyres: I used to love schwalbe magic Mary’s and they were great but made the switch to maxxis assegai/ minion dhr combo and definatley preferred them, dh casing rear double down front and always maxxgrip. I could only get 1 month out of a rear in summer but it was worth it for a good tyre.

sorry for the long post but it may be helpful to somebody out there.

These were the components I am markedly happier with after researching and proving their durability.

I'm glad Specialized tires are starting to grow a larger following. Nearly 1/2 the price of maxxis with equally if not better puncture protection and grip. I love my Gen 2 Hillbillys over any m product  previously ridden  and they grip better over slick roots, rocks- all sharp shale in my region. They are not lightweight but not the heaviest. Favorite tire ever so far, but my region is mostly wet an ungroomed.

Box Components Drivetrain: LIFE. TIME. WARRANTY- on almost any kinda expected damage. You can get 11 and 9 speeds, a super stiff multi disc clutch pack cut back on my chain slap and uses a 3D(metal) printed jockey cage. Like they looked at what works and tweaked it.The 9 speed still gives you a 50 tooth gear and reduces weight. I have the 11 speed but hear most people don't miss the 2 gears. Also like 1/2 the price of Sram or Shimano stuff. Shifting is accurate, crisp-enough. Haven't had to adjust in two seasons. What more do you need.

Wolftooth Fatpaw Grips. They look cool on enduro bikes and come in cool colors. Again, with my janky trails, the Fatpaw grips significantly reduced harsh lil vibes an reduced most of the arm pump/ hand cramping without feeling vague. Big help on long descents. They actually help me be aware of death-gripping so I can ease up but not lose control. Also come in smaller sizes and XC racers like em for a reason. I have medium-large hands and like how natural they feel in my grip, like an oversized deadlift bar or a chunky steering wheel on a sports car. Previously beaten up thin rubber sram grips felt like I was gripping twigs and would just beat up my hands on descents. Made me stress about my shock tuning, bleh. One downside is they can feel slick when completely soaked with bare hands, making you want to grip harder. With gloves it's not a prob. On my 2nd set and I'll never go back. Another downside is you have to cut em off but they're like $25.

Steel Coil Forks! Any of em! Cane Creek, Marzocchi, Ohlins and I love my Suntour Zeron- which can be swapped with their premium air spring. 35mm stanchions, magnesium lowers to save weight (lighter than a comp Marzocchi) and the same controls as the other expensive brands. I'd just rather not  fux with my shock tuning over a week then be forced to take it to someone to service. Once dialed they are fantastic on small bumps and reliable on big hits. For me the 1/2lb-ish weight penalty is meh. I can clean n service em in 15 minutes and swap out a taller/ shorter, stiffer/ softer spring.

After cracking my last aluminum frame (and Trek not honoring their warranty ) I have to agree with other posters;  erring on the side of Beefy. I really Like How Nicolai, Geometron, Privateer, RAAW and Norco build their bikes.  Also Reebs are super sexy. Any Steel bike : ). Again I'm not tryna win any competitions or KOM's. Just have fun.

+1 for Norco Sight aluminum frame, been racing enduro and downhill and just generally abusing one for over a year now and it's held up great. For another option, it's a little outdated but the previous-generation Specialized Enduro. I ran one of those for four years, I literally have no idea how I didn't crack the carbon frame. Put it through hell and back and it came out unscathed. 

Far as wheels go, another vote for DT EX471/511 with 350 hubs. Unbeatable setup.

Tires: in my experience it's very hard to beat Maxxis DHF/DHR/Assegai/whatever your preference is. 

Brakes: I ran Code Rs with almost no maintenance for forever, but they felt like shit. I've got Hayes Dominions now, slightly more finicky but once you get em working they're fantastic, and they've needed very minimal maintenance. 

Drivetrain: SRAM 11 SPEED!!! Could survive nuclear war. Most crucial part of a reliable enduro bike. Only modification it needs is a 46t cassette, then you're chilling on any climb. Plus you get the benefit of wowing all the dentists when you pass them on a climb using a drivetrain they didn't know existed anymore. 

Rear shock: I feel like you have to go with a coil for reliability. If a seal on an air shock blows, you're screwed, but you really can't screw up a good old spring. I've been running a Cane Creek DB CS Coil for a while, I did have to get it serviced when I got it but like my Norco frame, put it through a full season of enduro/downhill without maintenance and it's running like a champ. Heard very good things about Fox DHX and Rockshox Super Deluxe Coil as well. 

Fork: like others have said, I feel like any option that's not boutique is pretty bulletproof. My Fox 36 and old Ohlins RXF36 have both held up great.

Handlebars: Aluminum Chromag Fubars. I twisted a stem in a nasty crash and my fubars came out straight as they were new. 

Dropper post: OneUp. Add some psi once a season and you're good.

Impressed so many folks chiming in on the Norco Sight. And I'll add another to the list.

I've had my alloy Sight since April 2020. It can do 70 mile all day epics, big, tough enduros, does great in wet weather riding. Touch wood, but I've had no issues with the frame yet.

I've had a Lyrik on the Sight and had the opportunity to up-fork-it (160 to 170mm) for a couple weeks and it's very capable in that setting, only bummer is the taller axle to crown and bb height increase.

Getting an up-stroked shock is nice as well for a bit more travel. The Float X2 is pretty awesome on there, albeit a Fox product and they leave their consumers out to dry; if I had my choice now, I'd go with the new Super Deluxe. 

Saint or Zee brakes are quite impressive as well. I've had a mix match set of Saint front and Zee rear more or less the whole time of ownership, and they were spare brakes before that already with a couple years of use.

Carbon rims with a good warranty and some take off alloy backup wheels. 
 

frame: Biased since I own one, but Privateer have great geo, big bearings and seem built to take punishment. The design is spartan, you will only find things that are necessary, but it works. There are 5 or 6 161's where I live and mine is a 141. No issues at all and the oldest frame of the bunch just had the bearings replaced, only a couple were a bit notchy after 2.5yrs of use under a very strong and fast rider. 

hubs: DT probably. I'm currently on Hope Pro 4's and I don't recommend them. 

spokes: DT Swiss butted (competition?). All you need actually.

​​​​​​rims: Again anything from DT. I've tried several of their cheaper line of rims and even the rear on my ht that has close to 10.000km and is dented AF holds air fine. 

tires: Schwalbe MM Supersoft for the front, Big Betty or Hans Dampf Soft for the rear, depending on how loose and steep the trails are. Supertrail casings are a great balance of weight/durability and the MM just became available in Supersoft/Supertrail. 

brakes: My mate's setup of SLX levers with Zee calipers seem to be the best combo of value, power and durability I've encountered.

brake discs: RT76 have been fine for me, will probably look at thicker rotors next just to try something new.

brake pads: not fussy about those, I've been fine with almost anything I've tried. Mostly dry conditions here, so maybe that has something to do with it.

rear shock: Current Rockshox Super Deluxe Ultimate Coil with the HBO. Very adjustable, few things to go wrong, seen my mate get faster after he put it on his bike.

fork: In love with my DVO Diamond, so I'd go for an Onyx for proper enduro. Very tunable, great people to deal with, recommended base settings are a great start point. No issues on my fork apart from one incident, and even then I suspect the guy who performed the service messed up. Option 2: Any coil fork.

handlebars: Nukeproof HZN2 alu are comfortable, affordable, and should anything go wrong, easily replaceable.

headset: no idea, never had any problems with stock headsets (again, dry conditions).

dropper posts: Brand X are great for the price and very reliable. One Up if you are short and need max drop per overall length. 

grips: Ergon. Great shapes, lots of models to choose from, their rubber compounds feel nice and last forever.

saddle: personal preference, can't really recommend anything for another person's rear.

derailleur: GX 11sp. Or as I call it, the Kalashnikov of derailleurs.

shifter. Sram 11sp from GX upwards

cranks: anything from alu in 165mm

Bottom bracket. Not SRAM. 

chain: the mid price SRAM chains have been great. 

chainring: Steel SRAM NX. Lasts forever, can handle a rock or two.

pedals: Anything from Shimano, esp. their cheaper offerings. Will outlive many bikes.

shift/dropper cables and housing: Shimano

linkage bearings: no opinions so far, have been on hardtails forever.

frame protection/noise management tricks: MX tank protection film from a local moto store is cheap and comes in A4 sheets. 

Just to add my 2 cents:

I agree in general about DT swiss rims (specifically the EX series), spokes and hubs being good. But ironically, I rate DT swiss built wheels pretty low, their insistence on using 28 straight pull spokes is ridiculous, I am constantly tensioning my wheels and losing spokes on the rear. 

From experience, it's possible to break nearly anything given a hard crash or brutal case, and weird stuff happens (ex. rock strikes to downtubes or derailleurs on the roads between trails in whistler)... so sometimes reliability is secondary to availability of parts or replacements in local shops especially if you travel for riding or racing. 

In terms of reliability riding style, maintenance (including crucial bolt checks) and bike setup are just as important as the components themselves. If you are the type to push it and crash often especially in rocky terrain, I'd spring for aluminum components. Bolts which worked themselves loose caused me more $$$$ in damage in recent years (cranks, fork, and nearly a frame) than failing components. Setting a bike up stiff and with higher tire pressures - to prevent harsh bottom-ing and dings - helps for reliability but you sacrifice comfort and grip. 

Frames- something a few years into the product lifecycle which hasn't been flagged for reliability concerns. Search the forums to see what frames have issues, which manufacturers have rectified the problem, and which manufacturers are treating customers well. If you go used- definitely consider the second owner warranty / crash replacement programs. If I were in the used market today I'd be going for an alloy Ransom frame (bike rides incredibly well), alloy slash, or a specialized qualifying for warranty transfer (and verifying with a shop beforehand that it's covered). 

+1 on Saint brakes. First, the performance is mighty- Saints were released a decade ago and are still being run by some WC teams. They are nearly bullitproof, long service interval, easy bleed, and high availability/compatibility for spares in any part of the world. Get the cheap ice-tech rotors, but skip the $$$ and rattling heat sync pads. 

A MTB wheel should really have 32 spokes. Esp. now that wheel diameter has increased. Not only for durability, but for when they go out of true, smaller distances between spoke holes will allow for more precision and more chances of bringing the rim close to it's intended shape.

Here's my two cents on some components that stand out for me;

Hubs - Anything Hope. Ive got a Bulb from about 2007 that's still going strong on one bike. Easily findable and replaceable bearings, no faff, just work. That said, I do the think the drive side sealing was better on the Pro 2's and 3's than the 4's, seem to get thru freehubs a little quicker now. Can't speak for the new Pro 5's.

Spokes - Sapim Race, cheaper than DT Comp and do the same job.

Rims - DT EX471 going strong for me on the rear, no complaints. Sack off the the alloy pro lock nipples though and just use standard brass. Stans Flow MK3 on the front likewise. Did have a Flow EX3 on the rear but that failed at the spoke hole, hence the swap to DT EX471.

Bars - Renthal Fatbar alloy, 31.8. No need for 35, 31.8 is stiff enough.

Groupset - Shimano XT 12 spd, had it for a year now, no issues. Much better shifting than Sram.

Rear Shock - Rockshox Super Deluxe Ultimate Coil, absolutely bomber.

Fork - Rockshox Lyrik Ultimate. Consistent, feels great, easy to service and find parts.

Oh I forgot probably the best value to performance component on my bike;

Pedals - Nukeproof Horizon Pro Sam Hill Enduro. By far the best bang for buck of any flat pedal on the market, and chain reaction often do them on sale. Some colours are £54.99 at the moment, almost criminally cheap compared to the competition!

frame i'd go for a santa cruz C frame, megatower could be good, expensive but you get lifetime warranty and 3 times free bearings.

hubs  Hope pro 5

spokes Sapim d light

rims Dt swiss fr541

tires Schwalbe Magic Mary/Hans Dampf Super Gravity

brakes Shimano SLX

brake discs magura storm

brake pads ice tech metal

rear shock Rock shox SD coil

fork Marzocchi Bomber Z1 with push spring

handlebars One up carbon

headset Hope

dropper posts Bike Yoke Revive

grips Esi Grips

saddle Ergon SM Enduro

derailleur GX

shifter X01

cranks GX alu

Bottom bracket dub

chain xx1

chainring gx

pedals DMR Vault 

shift/dropper cables and housing Jagwire

linkage bearings Stock ones

Bottle cages none

frame Mounted tools EDC Tool

frame protection/noise management tricks Ridewrap

What an interesting topic, but on some parts i dunno if we could put a specific product but I'll try.

frame: Thats the trickiest one, I would say took the right frame and material for the right purpose, don't do dirt jump with a carbon DH DC fork, most of the time an good constructed alloy frame will ride for 4-5 years without any issue (as my last coal V2 did). Next level would be to ride a full cromo or partial cromo / alloy or cromo / carbon mix frame, full carbon are stiff and durable in time but a crash could crush it without any possible repair, so i will go for heavy metal on the next one.

spokes: DT champion 2.0 use it for decade on differents wheelset (DJ bike / enduro / dh) a bit heavier but still ok, even when my hub flange crushed in skate park the spokes were ok to be rebuild on the next hub, 10years later.

rims: I do like the reverse components Black one, not that heavy, handle the enduro riding well. IF i'm not worry about weight, give back atomlab DHR rims from the garage.

tires: DH casing, the new Michelin DH line is pretty cool.

brakes: Formula Cura, light, powerful, simple, and cheap.

rear shock: Coil are reliable, mostly all of them.

fork: Formula Selva, 5 years of use on 2 frames, never had any issue, seals / oil service once a year.

dropper posts: BikeYoke Revive, same story 5 years any issue, any play anywhere, incredible product.

derailleur: this is where things to me more personnal, the best performance price is a GX, i tried the SLX/XT, but the clutch system is annoying and giving some troubles, definitely sram GX, after months it could be less precise with some play inside, but it still works.

cranks: Race Face Turbine, lightweight, good value price, simple design.

pedals: Concave shape that's it. Reverse components Base, DMR Vault, Tenet, if you can ride it with low height pins, you get the right pedal.

Bottle cages: Fidlock is pretty cool, use it for years now, really clever system, never lost the bottle.

frame Mounted tools: the little tire plug easy access, that's all.

Frame: Anything from Nicolai, especially the G1. These things are built well and not for weight-weenies.will survive pretty much everything.

Wheels: DT-Swiss are great, even entry level E1900 are pretty good.

Dropper: BikeYoke is the best. If you are on a budget, BrandX and so on work pretty well as well. No Reverb!

Brakes: Formula Cura 2. Sram has good parts availability but needs quiet a bit of service in my experience. Had leaky caliper pistons a few times and stuck lever pistons on the older Guides. maybe it got better, I don't know.

Shifting: GX 1x11: Reasonably priced and you can still adjust the clutch with a little trick. Took me 5 years till the derailleur wore out.

Pedals: Shimano DX PD M647. they keep on working.

Yoda said it well, anything can break. Crashes happen etc.

I'll add, that even the best products from manufacturers with good qc can have defects occasionally. If minimizing down time is the goal then it's hard to do better than having a second bike. It's also nice as it allows one to have bikes in different categories to make other trails more fun. Like having a hardtail or short travel rig to make flatter trails more fun than they'd be on a big bike.

Edit: And obviously having both bikes be the same wheel size, hub widths, etc to keep parts as interchangeable as possible is a big help too. 

My thoughts when building up my last bike were exactly the subject of this thread. After a few seasons of constantly breaking parts (frames, wheels, drivetrains mainly) I have settled on what I believe is the most reliable enduro and bike park rig. This is entirely my opinion but last season has shown that it stands up to the abuse, especially when compared to my mates' rigs ridden at the same level on the same trails.

Frame: Transition Spire Alloy

Suspension: Fox Factory 38, Rockshox SDLX Ultimate w/megneg

Wheels: WeAreOne Union front, Strife rear

Brakes: TRP DHR Evo; sintered pads, 203mm rotors F&R

Drivetrain: Shimano XT/XTR 11spd

Cranks: Alloy Raceface; 30t chainring (gets changed out)

Dropper: Fox Transfer Factory (If I was going to change this I'd go to a OneUp, but I'm a sucker for the Kashima)

Tires: Currently on Conti Kryptotal F&R; enduro casing (only a handful of rides on these so far, not conclusive but great so far). Previously on Assegai/Assegai and Assegai DHR, always Exo+ front and DH rear

All other parts not listed I've found to be completely subjective and up to personal preference. Basically, everything on the market works.

This setup has been damn near bulletproof for me (knock on wood) and it's been the most fun bike I've owned.

Add a set of the semi goofy looking hand guards. In a crash they can save your levers.

A few things I would add. Durability for me also means being able to work on it yourself with little fuss / not having to constantly work on it. 

I’ve really not been impressed with Shimano brakes in terms of durability. Saints and XTs I’ve had worked well (except for wandering bite point) but it’s not encouraging to see how quickly the fluid becomes dirty. Maybe it’s just me, or not cleaning inside the caliper enough, but I had to replace the ceramic pistons and seals because they wore out. You can get metal pistons for them, which may be your only option when they wear out. 

SRAM Codes for me have been much more durable, almost set and forget for years with an occasional bleed and piston clean in dusty environments, just to keep the feeling snappy. Curious about the new Hopes now though, their stuff is dialed.

I’ve loved the OneUp dropper - super easy to service unlike a Transfer or Reveb. Can also be shimmed up/down should you break a frame and go to one with a different seat tube length.

Also love OneUp bars, despite carbon maybe not being your first choice for durability, they are super comfy in their relative flexibility. Avoiding 35mm bars is another good option if you struggle with arm fatigue.

+1 all the recs for DT Swiss wheels too, so good! Big fan of cushcore here for helping avoid punching holes in tires and extra helping of IDGAF in rock gardens as well. Or DH tires.

Also run a front fender all the time in dusty / wet environments. A marsh guard or one of those little guys as long as it protects your fork stanchions from the tire can keep your seals less dirty.

Also! Only sorta off topic, but suspension maintenance is super important to keep the bike feeling good.

In a season of racing I’d probably shoot for 3-4 lower leg oil changes on the fork and 1-2 air can lubes on an air shock? Maybe none on a coil shock unless your DHX2 is going to blow up? Thoughts?

Simple fork / shock service is fairly easy to learn so you’re not taking it to a shop multiple times a summer.

Love this question, a few winners for me after smashing more stuff than I'd like to admit:

11 speed drivetrain - I've been running shimano der/shifter with sram 11s cassette for years, no issues and derailleurs are cheap and available for replacements. Tried 12s X01 and everything bounced around too much and wore out. Plus 11s is lighter anyway

EX471 rim w DD and cushcore. I think 30+mm rims are overrated and the 471 just won't quit

Formula Selva Fork. For suspension I'd say ease of service is just as important as reliability and the Selva is a dream to work on

Also, get a torque wrench and use it 

I love this topic, and have also tried to build up my own low maintenance enduro bike. I have a bad habit of breaking stuff, and I hate missing rides or wasting money due to parts that couldn't handle heavy use. Ain't nobody got time for that.

I'd echo what people said about SRAM 11-speed. Set it and forget it. I'm convinced the 1195 X-dome cassette is made of Adamantium. I was several thousand miles into an 1195 cassette that I got for $20 from a friend who'd already put several thousand miles on it, and I only took it off because I got a deal on some fresh 12-speed stuff. Invincible.

i dont understand the whole cushcore/dh tires thing, ive run exo+ and maybe DD in extreme cases(w/o cushcore) and i havnt flatted in over 3 years.

If i go casual riding i have to run EXO+ or the bike is a dog to ride - maybe i run proper pressure and have no issues??

I'll take "reliable and cost effective" a step further, and add bulletproof, and self serviceable.

Frame: Plenty to choose. Just pick aluminum with a threaded BB. I have several Canfields, and haven't broken them yet.

Wheelset: DTSwiss 350 hubs (36 tooth max), EX511 hoops, DT Swiss Competition DB spokes, 2.0/1.8, brass nipples 

Crankset: Shimano Zee, Renthal chainring. Angular contact bearing (Enduro) bottom bracket. No need to use anything more than the chromium ball variety. Ceramic and SS just wear out the race faster.

Pedals: forged aluminum, I use the Stamp 7's.

Shifter/rear mech: Shimano XT, Sunrace cassette, SRAM or KMC chain, 10 or 11 speed. Shimano rear mech clutches are adjustable and rebuildable. and they keep shifting when dirty. Skip the 12 speed groupsets and hollow pin chains.

Brakes: Shimano Zee, MTX red pads, SRAM speedline rotors 

Fork: DVO Diamond D1, Shock: DVO Topaz (air), DVO Jade (coil). No specialty tools required, and are totally user serviceable.

Dropper: Any PNW, but whatever you run, use a Wolftooth lever.

Bars/stem: Raceface, Nukeproof, Renthal... aluminum, whichever rise, back sweep, length and width works for you.

Grips, saddle, tires... all personal preference.

I may not have created the lightest build, but that wasn't a requirement per the OP. LOL

I went for this exact goal last year when I built my EVO, goal was a heavy trail bike/enduro ish build that I could ride anything from local XC trails to bike parks when I don't feel it warrants taking my DH bike.

I built this bike for $3600 using a mix of new/used and take off parts I sourced locally and on Pinkbike.

Used S5 Alloy frame

ZEB ultimate (super sale on the first gen when the new ones came out)

Super deluxe ultimate with Meg neg

Used Cascade link

Code RSC new take offs bought on pinkbike

Sram Centerline rotors 

12 speed SLX full drivetrain/cranks

Closeout Hope Fortus wheels with pro 4 hubs, rear is heavier reinforced DH rim, Front is lighter enduro rim. 

Michelin Wild Enduro tires. 

Dropper, Handlebars and Stem were all stuff I had laying around

Bike has been great so far and am excited to get out on it this season, for now ill just talk about it on the internet as I'm still healing a broken scapula.

Things I can’t recommend: nx or GX Eagle anything other than the cranks. Deore 12 speed derailleur. OneUp bars, broke 2 of them! Renthal push on grips. SRAM guide brakes, G2 are ok-ish with 200 rotors but not for steep double black stuff. Deathgrips seem nice but don’t last long. Trail 1 carbon bars (feel like iron) and stem (mine wasn’t machined properly). AXS anything. Gravel bikes. Road bikes. Group rides over 5-6 people. Roval or Giant wheels. Formula hubs. X2 shock. Absoluteblack chain rings or singlespeed rear cog.