Before he goes for the winner of Pacquiao-Hatton, the two names that I have heard continuously thrown around were Mosley and Marquez. Between the two, who would you rather see Mayweather fight? Personally, to add to his legacy, I'd like to see him fight Mosley. I think the weight difference between him and Marquez is just too much. Besides, then no one can say anything more about him not taking on real challenges, granted I think Marquez, even being the smaller man would still be a challenge. Post em'.
I voted for Shane because he's naturally a welter and could give Floyd some problems, but not unsolvable problems for Floyd.
Jmm has just moved up to Lightweight and would be giving away too much weight to fight Floyd even at 140.