I predict both of them taking a vicious beating.

I will edit this later after I think of all the possible intangibles and predict an actual winner.

EDIT: Ok after thinking this through, I am going to go with Mosley as the winner. The only opponents that have ever given him trouble offered great speed and defense. He will be in a tough fight, but I will predict Mosley winning by round 10. I know this goes against certain logic in that Cotto usually has an opponent worn out late in a fight, but I think Mosley is the type of guy, that has the speed, power and overall ability, to do the same to Cotto.