Gotta say Fedor is #1. Not only because he only has 1 loss in his career (from a cut stoppage), but because of how he beat the people he beat.
Everything from chasing Cro Cop all around the ring and outstriking him, to pounding Nog into the ground from Nog’s guard, to getting slammed on his head by Randleman and then immediately reversing him and submitting him, and the list goes on.
Basically the guy dominated people at their own game. That’s no joke.
After that though, it’s gets a little tougher to call IMO.
Anderson is a phenomenal striker and makes people look stupid on the feet. But he’s got weaknesses and usually wins by making his opponents fight his fight.
BJ Penn is one of the most gifted athletes in MMA history and pound for pound might be the best MMA fighter out there. Maybe GSP and Yamamoto might come close though.
Hughes was the most dominant champion that the UFC ever had in any weight class.
Randy has been world champ in two weight classes.
Nog has beat a lot of stiff competition.
Henderson has beat some of the best light heavyweights and heavyweights in the world.
You’ve gotta love Bas.
Then you’ve got kind of a grab bag of Wandy, Chuck, Lindland, Cro Cop, Tito in his prime, Frank in his prime, Coleman in his prime, and maybe Saku or Royce in his prime.