I'd obviously love to see both, but I voted for Mayweather - Cotto. Based purely on the SSM fight, I think Cotto might have the tools and timing to trouble and maybe beat Mayweather (though Cotto didn't look as impressive once SSM started boxing and moving more). Mayweather needs to fight the best of the welterweight division, and the only three fighters I want to see him agaist after the Hatton fight are Margo, PW, or Cotto and I'd much rather see him face the last two.