Pac or Cotto. choose your poison both knock him out. The exact type fighter he has avoided since Castillo 1. Coincidence he risked losing his P4P #1 title to not face two of the more popular fighters in the sport. Every human on planet earth except for *****s agree. So 99% of planet earth agrees that Floyd ducked Cotto and Manny Pacquiao. Cotto - No wobble just flat out beat his best resume at WW. KO'd Judah. Beat Shane in 2007. hypothetically Floyd's tune up should be against Cotto to make sure he will not get hurt vs Manny.
There is only Pac that who would definitely beat him at that weight. Khan if he keeps improving might beat him at trashtalking though!
Pacquiao is the biggest, and possibly only threat to Mayweathers '0' at 147lbs. Pacquiao can beat him (even though I favour Mayweather in this match-up).