The brand of the bike essentially only means who made the frame (or who put their logo on it). All of the other parts are more or less interchangeable with other bike brands so I wouldn't say there's any that's particularly anti-repair. If you know how to work on one bike you know how to work on all of them.

For a quality hardtail I'd say the price range is between 1000 to 2000 bucks. My Kona Kahuna cost me around $1000 and it has served me more than well. For someone your size definitely go with L or XL size frame and 29" wheels. Then just make sure it has one-by drivetrain (1 cog in the front), hydraulic brakes and an air-shock. If it comes with a dropper post aswell then great but it's not mandatory and you can get one later aswell.

I bought a Rose Count Solo 3 on sale recently for 800 euro and put on a dropper, pedals and bottle cages for ~200 euro and it has everything I wanted from a mtb. Hydraulic brakes, air fork with remote lock, a 1x narrow-wide chainring and a deraileur with clutch.

I'd say 1000-1400$ gives you a capable hardtail that doesn't feel like you paid too much for something you don't actually need.

Check out manufacturers and retailers, a lot of bikes are on sale right now.

I got a Kona Unit a few years ago (oh my, it’s been almost 10…). I ended up swapping in a 1x9 drive train. It’s a sturdy and basic bike , you can upgrade as you go. Its almost doubled in price since I got mine- try used?

My Surly long haul trucker has lasted almost 20 years of off and on abuse, and various configurations. If you can find a used Surly that’s in good shape I’d recommend. Also Soma, choose your frame and go from there- spend what you want for the bits that you want/need.