Which fighters suffered the most through sharing an era with another fighter?

Absolutely. Monzon was appreciated by two demographics: Argentinians and purists. He should have been appreciated by far more.
Duran showed a bit of jealousy when he made the comment about wishing he were big so that he could kick Ali's ass.

Duran did not really become a national figure until the talk began about his June match-up with a certain WW who liked to do the Ali shuffle and mug for the crowd. So there we have the Panamanian... overshadowed by Ali throughout his LW reign of terror and only given worldwide attention when he challenged the one who was given the Ali mantle by the cheerleading American media. No wonder why he wanted to kill Leonard, by so doing, he would also vicariously kill Ali himself so to speak.

 

While this is true it has been said that those who both ducked him and saw him fight melted.