Williams is an overrated sloppy fighter who got exposed by B- level fighters like Quintana and Cintron and really lost to the better fighter in Martinez.' Martinez > Cotto > Williams
Mayweather fights for money, Cotto would make the most of the three. P.s. Have a look on boxrec, you might be surprised to see that Williams didn't actually lose to Martinez or Cintron, he won. :good Cintron deserved to lose for being a *****. Williams did just enough to beat Martinez. A draw would have also been a reasonable result in that fight.
In this order... #1. Manny Pacquiao #2. Andre Berto #3. Whoever is the top dog @ 140lbs At the time. (Bradley/Alexander/Khan/Maidana/Ortiz ect....)
If the first one happen your going to be disappointed by how much Floyd will own a smaller man. Floyd with an advantage come on... 2 EZ.
1. Pacquiao 2. Foreman/Cotto winner (Foreman) 3. Who ever emerges out of Martinez, Williams & Cintron. (Martinez)