Joshua - Wilder will potentially be bigger than Ward-Kovalev but not Canelo-GGG, Canelo's the biggest star in boxing at the moment and GGG is one of as well, it'd sell well. Just look how many topics even on this forum have been made about it, must be thousands now.
I agree that Canelo GGG isn't the biggest fight in boxing right now in terms of revenue generated. I think Fury Joshua in the UK probably makes more $$$ than any other match up right now..
Floyd fans against GGG-Canelo taking place because it would be the coronation of a pale skinned guy as a superstar.