new BIKEPACKING Rig

Howdy!
Coming back from my cross-country Netherlands trip, I realised that I wanted to dive deeper into the territory of bikepacking and, more importantly for this post, buy a bike that is up to that task. I am currently rocking a single-speed city bike that won't cut the corner for anything but tarmac and flat roads (which the Netherlands luckily offered in abundance).

For the past few weeks, I have been searching on eBay and the likes to find a mtb that fits my budget (ideally not more than 1.5k) and its intended purpose.
The purpose of the bike is to be able to ride anything but technical/ hard single trail and to have reliable components that won't feel incredibly sluggish when going up a steep mountain pass or cruising down lengthy roads (maybe a lot to ask for in one, cheap bike...). The only problem is: I have no clue - I am a bloody beginner and whenever I see a good deal (I really want to buy a used bike/rig for price's sake), I can't be sure it actually is worth the money I would be willing to spend. Hopefully, some of you bike masterminds can help me out with that 
I have an inseam of 90cm and I am 1.83cm tall.


Here are some options I have collected so far:

#2 Surly Karate Monkey (1500$)

important specs:
front suspension: RockShox Reba RL 29" 140mm
front wheel: DT Swiss M 1700 Spline Two 22,5
rear wheel: DT Swiss X 1900 Spline 22,5 Boost
brakes: Magura Mt Trail Sport

While I really fell in love with the Kona, I think you get even more for the same price here, right?
At least it sounds reasonable priced for me. I am only concerned about the Large Frame, it might not fit me perfectly...

#3 Salsa El Mariachi (1450$)

important specs:
DT Swiss wheels
Syncros saddle post, stem and handlebar
singlespeed - would have to upgrade/change that (for another 100-200€?)
surly front hub

DMR Bikes back hub (with space for the casette)

SRAM Stylo crankset, SRAM Elixir CR Brakes

Out of the 3: Kona, Surly and Salsa it is really hard to make a decision now. The Salsa seems to be in excellent shape and received a lot of love (only clocked 300km as well)
but I would have to put a bit more work into it, compared to the other two.

I expect to ride 20% paved road, 60% gravel and 20% trail, but since that changes with every route, it is only an estimation.
What do you guys think, are all 3 fairly priced, or should I keep looking?

Thanks for any answers in advance!