Mayweather, UD. Pacquiao's weakness is counterpunchers (like Marquez). Well, Mayweather is the best counterpuncher in the business and makes great in-fight adjustments. If Pacquiao does not get to him early (first 4 rounds), Mayweather will have him figured out and cruise the rest of the way. Don't think Pacquiao hits that much harder than Maidana, so power might not be much of an advantage. Pacquiao's power is due to accumulation of power shots, as he lands a lot of them off fast combinations. Don't think he'll hit Mayweather enough for that to happen.
Like someone else mentioned, one of Mayweather's weaknesses is non-conventional fighters. Punching from different angles will help Pacquiao, just like it did for Maidana. He should also try to get Mayweather on the ropes as much as possible (easier said than done), as Floyd's defense is worse against the ropes and he tries to get cute with his dodging and not keeping his hands up when cornered. Should be a good fight. I would say I'm 80% confident of a Mayweather win.
Totally agree, but Floyd doesn't have near the KO power that Marquez has.
I don't think there's a big power difference between Manny and Maidana either, but the difference is Pac's speed and weird angles. Power is much more effective when the other guy doesn't see it coming.
If you remember the Mayweather v. Mosley fight, Sugar Shane rocked him early in the fight. And Mosley was never a guy with one punch power. If Pac catches him the same way, Floyd crumbles. But I agree that the likelihood of that isn't great due to Floyd's great defense.