Further to Kastrups advice i would add.
Look at what are the common bikes being ridden around your locale. There aren't many bad bikes out there nowadays, but theres bad places to use a particular bike. A 6" travel 29er isnt going to be much cop if all your riding will be in tight twisty woods. Likewise a so-cal designed bike doesnt like mud- take note Specialized
Don't expect the purchase of your bike to be the end of your spending. Better to buy a cheaper bike, and save some cash for when you rip a rear mech off, or after a few grotty rides, you need new brake pads, new chain or stack it and bend your bars, or whatever.
Contrary to what the industry would have you believe, the 26" wheel ain't dead, and won't be for a long time, so if thats the bike that fits your needs best, do it. Don't fall prey to the wagon wheel fashion.
Avid brakes- they are so unreliable, try and steer clear if you can.
My ideal bike, while not perfect would be a 26" wheeled trail bike with about 5" travel and an XT groupset.
Does most things well, and the rest of the time it will get by.
Hang on, Giant already make it- Trance X1