There’s no simple answer to this question for me. I think each opponent serves a purpose for certain circumstances and objectives. If we said of all-time, the Anderson Silva fight is definitely the right way to go. Considering that two clear candidates for greatest of all-time title were competing in their primes at the same time and separated by only one weight class makes this very obvious. There was also a point when both men had essentially cleaned out their divisions and the UFC was haphazardly throwing whoever could amass a win streak or the semblance of fandom to challenge both men.