i have a trek session 7 and its great, i got for 700. Its a badass bike. The Transition bikes are good but they are a tad expensive. I would suggest the Session
what kind of riding will you be doing most? the bottle rocket is more of a slopestyle/4x bike. the 77 will be more of a dh and freerider bike. not too much of a dh race bike though. i'm not totally sure what the Preston is. i don't really like them so i never really paid much attention to them. they seem kinda weak, but that's just my opinion. my friend ripped on one for a few months and loved the thing. another one of the guys i have ridden with has the 77 and he loves it. he does all kinds of shit on it. he's done xc rides on it, but he has raced it before. so it can be used for everything. he was hella slow on the xc ride. what do you expect from a 44 pound DH/FR bike?
The trek is also quite heavy, Bottle rockets arent that good, prestons are okay. I sujest that you look for a really nice used bike. You will get better value and a good price.
I would say get the Preston i've rode both the Preston and Bottle Rocket. If you want to climb but still be able to schmab downhill and do some free ride the preston should hold out, just throw a more burly fork on it like a 66. The Bottle Rocket is super nice and hadles well but is a tad more heavy.
i have a trek session 7 and its great, i got for 700. Its a badass bike. The Transition bikes are good but they are a tad expensive. I would suggest the Session
dude. don't trust a bunch of guys that you've never met in person, and that your only talking to on the internet. go with what fit's your riding style the best and what's in your price range and what you feel comfortable on. the more comfortable you are, the more confident you are. and the faster you are and the bigger you'll be able to go. that's what you need to decide.