Close call, I'll probably go with Mayweather. If Cotto beat Margarito, then it might be even. Cotto destroyed several good fighters/prospects on his way up at 140 like Ndou, Corley, Branco. Guys like Maussa, Pinto, Torres, Malignaggi, Quintana, Foreman were all undefeated when Cotto beat them.