I do not believe one is best. I have a normal Prophet and Dialled Alpine and a Titus Fireline 29er. All of them are great on their own terms.
I built a pumptrack in the garden and surprisingly the 29er is easiest to pump. Probably due to it flattening everything out and just flowing better. The Dialled Alpine takes more effort to pump but the more energy you put in you get out so it is easier to get air and you can go faster.
The Titus makes roots and rocks much easier and means that you are not expending so much energy and can go faster. Jumping and pumping you feel less connected with the bike. The Prophet is still my fav bike for mountain biking though as it does everything from DH to XC.
With all this talk of wheel size and now 650b got me thinking that since all wheel sizes cannot be optimal for all uses what is each size best at?
I suppose the smaller the wheel size the more manoeuvrable the bike will be and the bigger the wheel is the better it will flatten out everything.
Personally I think most people would be better off with a 29er now as most people do not do jumps or techy stuff. For me my 26er give the most fun and involved ride, which I like and is why I love riding a hardtail. If I was going for all out speed though the 29er would be my choice.