Arguello, as was already mentioned. We're all forgetting an obvious one: Sugar Ray Robinson. Who seriously hates on him? Anyone who mentions he's even slightly overrated gets flamed out of ESB like a fat woman out of a buffet.
Marvin Hagler. Also I dont know how someone can hate Pacquiao hes the perfect champion: skilled, tough, exiciting and respectful.
In answer to some of the other suggestions in the thread: Johnson - styles himself as road warrior despite having had a greater percentage of his pro fights in his adopted home state of Florida (where he's lived since his early teens) than Joe Calzaghe had in Wales. Constant whingeing about alledged roberies that were actually close fights where he didn't do enough. Mosley - drugs cheat. Are you kidding me? Katsidis - Australian. Enuff said.