I still think Anderson Silva is the best pound-for-pound. He maybe needs to lsoe a fight to get the hunger back, but he is unbelievably athletic and clinical.
I agree with that. For me, it's really difficult to measure the "best" in MMA, but Anderson Silva ranks up there with Fedor in my opinion. His last true loss was by "Flying Scissor Heel Hook", which if you watch the replay, was just about the most amazing thing I've seen (and also extremely lucky and difficult...you never see that move at this level).
I may have mentioned before, but my buddy Roli was on TUF 8, and he had a little time to workout with Anderson, and said his training techniques and mindset are simply astonishing.
Guys like Anderson Silva, Royce Gracie, Fedor...are so methodical in what they do...it just looks so easy to them.
Edit: And a big edit for Nogueira, who is one of my favorites all time. A dude who went the distance not once but twice with Fedor...