Floyd Mayweather jr. vs. Donald Curry- I think I'll go against the grain here and say Curry. I just have not seen enough from Floyd at this weight to say he'll beat any of the top all time welters.
Sugar Ray Robinson vs. Carlos Palomino- Robinson by late KO
Sugar Ray Leonard vs. Oscar De La Hoya- Great fight but Leonard would win
Emile Griffith vs. Henry Armstrong- Can't vote on a fighter I have not seen
Felix Trinidad vs. Kid Gavilan- Same as above though the fact that Gavilan wen't a total of 25 rounds against SRR is bad for Tito, still the Kid loss to some nobodies early in his career..
Thomas Hearns vs. Simon Brown- Hearns KO
Pipino Cuevas vs. Pernell Whitaker- Whitaker UD though it would be entertaining
Jose Angel Napoles vs. 'Barbados' Joe Walcott- Again, I have not seen Walcott so can't pick a winner. Joe seemed pretty tough though and I can see him beating "Mantequilla" similar to the way Monzon did.

I think guys like Hearns, Robbinson and even Trinidad had the power to beat anybody in any given fight. Robbinson and Hearns also had some great boxing abilities. What puts Robbinson on top is that to top it all off he had a granit chin.