Single track trails. It's not very rocky around here, but steep is fine.
Prepare for a long winded post, but mountain biking is an activity I’ve become very passionate about over the last year and a half.
First: You want tubeless. Any bike with a non-tubeless compatible wheel set is a non-starter for me. Wheelsets are expensive to upgrade and nothing sucks worse than getting a flat while in the middle of nowhere. In the old days I remember constantly getting flat tires, but on my current bike running tubeless I am up to 1,750 miles with no flats. I’ve worn through a rear tire with no flats.
Second: You want a dropper post. I don’t think any bike you listed had one, but it is a total GAME CHANGER. Gone are the days of stopping at the top of the hill to wrench your seat post down. The ability to raise and lower your saddle at the push of a button is amazing and helps in all aspects of mountain biking.
Third: The price of bikes has increased dramatically from two years ago, and the spec has also gotten worse. I don’t want to come across as snobby, but I’d encourage you to increase your budget to 1,500-1,750 as that is the price point you get all of the quality of life features. If you are going to be a MTB coach I assume you will ride a lot, so you might as well have a bike that makes it more enjoyable.
Fourth: I ride using a SRAM groupset, but I have heard Shimano Deore is better than Eagle SX. I have SX on a hybrid bike and put over 3,000 miles on it before having issues, but I suspect it would fail much faster subjected to the punishment of mountain biking versus road riding. My mountain bike has NX, which is one step higher and I have 1,750 miles on it with no issues. I’ve heard good things about Microshift Advent X, but I will say that while it’s probably sufficient for a lot of rides, when you need more gearing the 1x12 is the difference between hiking your bike and riding
Fifth: Avoid bikesdirect. Their frames use wildly outdated geometry and while you used to be able to get better components for the price that isnt really the case anymore. The frame geometry has the biggest impact on how the bike rides.
Sixth: Consider used if your budget isn’t FBG level. Some bikes that I think are pretty solid for the price are the Giant Fathom, Canyon Stoic, Kona Honzo, Trek Roscoe 7+, Ragley Big Al, and Vitus Sentier. I ride a Commencal Meta HT that I bought used.
Hopefully this helps. It’s a hobby I’m wildly passionate about but have so far avoided dropping $4k+ on a bike.