Welcome aboard, you're in for one helluva experience on here. My advice is to demo a few bikes at a few parks. Halters usually has a decent demo fleet, and you could wait for demo days for brands he doesn't carry.
Don't just buy a bike before demoing it on the trails you ride normally. I was all settled in on an Intense ACV until I took out a Santa Cruz for the day a few times. Also try 29er and 27.5 just to get a feel for the difference. Good luck and take your time deciding.
