Maybe my all-time favorite. The guy always came to fight, and fought anyone and everyone regardless of weight class. Very exciting fighter, and probably the most creative in-ring as well. His flying M. Bison-style divestomp to Vitor Belfort (twice!) is still one of the most hilariously awesome things I've ever seen in my life.
Took me a long time to love Wanderlei, after the BRUTAL beatdown he delivered to Kazushi Sakuraba. But Wanderlei, like Sakuraba, fought anyone and everyone. And he did it fearlessly and aggressively.
This is a guy who had a good enough ground-game to take opponents down and grind them out, thereby preserving his health. But, for the fans, chose to stand and bang it out each and every time. Even against guys who massively outweighed him like Cro-Cop and Mark Hunt.
I remember in Pride he even gave his phone number out to fans and told them to give him a call, his only rule being please not to call so late, to avoid waking up his wife and baby. (named Thor!)
Stoic and massively skilled. The pound-for-pound greatest fighter in MMA history. The man is everything a Mixed Martial Artist should be.
Anyone coming in here trying to argue for some ass-shaking faggot equipped with pink shirts and cosmetic glasses please save your breath.
Other fighters I've liked at various times:
Genki Sudo ("We are all one")
Mauricio "Shogun" Rua (Hyper-aggressive)
Akira Shoji (True warrior)
Dan Henderson (One of the best American fighters for a long time)
Quinton "Rampage" Jackson (Pride version)
Chris Leben (A real-life Zombie)