What was floyd mayweathers hardest or best win?

There arent any.

But if we rewind history and pretend floyd got cut or perhaps a few knockdowns or floyd was gassed in the last rounds with any opponent thats what makes a great or best opponent in some peoples eyes...

How about they were all hard great opponents but they didnt effect floyd like that might have done in their own respective careers with other opponents.

Calzaghe gets alot of abuse who may not have dominated all his opponents like floyd does but deserves the same respect as he stayed true to boxing.