I would like to see Mayweather fight Sugar Ray RObinson just to prove he is better.
Roy JOnes Jr. vs. SRL, Hagler, Hearns at middleweight or super middleweight
Winky vs. Duran at super welterweight
Ali before exile vs. prime Mike Tyson.
Whitaker vs. Mayweather Jr.
Tszyu vs. prime JCC
JCC vs. Duran
Hearns vs. Trinidad at welterweight (I think Hearns would kill him, but one punch could have it the other way)