Exactly...! In terms of skill, you can possibly make an argument as to why Mayweather belongs to be mentioned with the fighters you mentioned, but in terms of resume, and legacy, sadly Mayweather did not take a page from their books....Floyd always took the easiest route, even if it meant ducking/retiring/avoiding/refusing to fight the very best he could have fought.
Pacquiao is smaller and is the better p4p fighter. Pacquiao fighting at WW now is like Floyd fighting at 168 and challenging Ward.
Manny's natural prime weight is 135. He fought at that weight once. What he has accomplished fighting so far above his natural weight is amazing.