All jokes aside, I think Mayweather would win. Close fight though, Paul is pretty much forgotten for some reason.
Probably because his reign was very short. He was excellent in his title-winning performance over Arroyo. Really beat the ever living shit outta Arroyo, and Arroyo was never the same again.
This fight could be fun, or it could be very dull. They both had a lot of pop in their right hand so that could lead to some real gunslinger type exchanges. I think that Mayweather is the more vulnerable guy in that type of fight. So he would probably utilize his advantage in mobility- Roger could flat out run when the mood took him and I remember Paul as being more purposeful- and the fight would never really get started.