I have a paranoia about carbon MTB bikes that I can't get over, they are used by a lot of people with no problems, I have had carbon road bikes and would have no hesitation on buying another, I suppose its because I have had some spectacular off's and knocks on my MTBs and maybe I am unduly worried a carbon frame wouldn't stand up well, I once saw a bloke come down Holme Moss second time out on his new Giant road bike, he was going far too fast and hit the wall at the first bend down, his frame was in two pieces, his knee not much better, a steel or alluminium frame may not have survived also, but it still bothers me.
I like Cube bikes, I put one together for the lad next door, a Stereo I think, good spec and good price, there are some real bargain 26 ers to be had, I got a Genisis Core a few years ago at a very good price.
My preference nowadays is 29 wheels, they roll over things much better than 26, but are a bit more of a hanfull on technical stuff.