Come on bro, other than Nog (x2) and Mirko, who did Fedor beat when he was champ?
He became the #1 HW on the planet in 2003. After that he remained undefeated for 7 years, also obtaining the #1 P4P spot which is unheard of before or after for a HW (minus Dana all by himself trying to sway the rankings now to benefit a HW with exactly 1 win).
In that time he beat basically every single ranked HW of that period (minus three that fate robbed us of in Josh, Sergei, and Randy) to include Nog, Herring, Coleman, Randleman, Sylvia, Arlovski, Hunt, Cro Cop, and fought a beyond-active schedule also having no blemishes vs a litany of HWs that all had the HW-puncher-chance to upset any of his fights.
He did all this in the golden age of HW, which had more skill than any time before or after, and which looked 100X times better than today where there grappling is almost nonexistent and the premeire org somehow gave a dude who had 0 grappling and fought 0 grapplers in his lifetime two title shots.
In addition to dominating his division, dominating P4P rankings as a HW, and having the most ranked wins of any HW in MMA history, he always came to fight to finish every single time (making his streak of not getting caught even more amazing). He, more than any other HW in MMA history, had the most obvious "Tyson effect" where his opponents were intimidated before they even competed against him. He also was always the most well-rounded HW in the sport (both before and after his era) and represented the sport as a complete mixed martial artist.
He also did all this while never cheating.
So yeah... Fedor.