If you mean best hands in terms of just punching power, I'd probably say someone like Wanderlei Silva, Dan Henderson, Takanori Gomi, or Chris Leben.
If you mean best hands as in the overall package (power, skill, speed, etc...) I'd say it's a toss up between guys like Andrei Arlovski, Quinton "Rampage" Jackson (best boxing skills by far), George St. Pierre, Antonio Rodrigo Noguiera, and several others, though Anderson Silva right now is looking like the badass
Chute Boxe always claimed he was back in
Pride.

@ Chuck Liddell and BJ Penn.