Pac and Martinez have the best shot. Cotto was always too slow, Khan is nowhere near ready for that stage yet, (although you argue that the fact that he spars consistently with Pac at least gives him a leg up on Ortiz, who was completely green and not ready for the world stage) and Margarito might have a slight chance of overwhelming him with volume and size, but between Margo's lack of speed, tendency to start slow in the opening rounds, and block punches with face defense Floyd probably could outpoint him. The chances of one or two of those guys eeking out a win in their prime might change a bit, but that's how I see it right now.
I picked none, but Martinez would be the most likely to win by a fair margin. That said, people forget that Martinez has been hesitant to throw against slicker fighters in the past (Cintron, R. Williams), just his last few fights have all come against guys who are pretty straightforward defensively (Pavlik, P. Williams, Dzinziruk).
Nobody on that list beats Mayweather IMO.... Pac would put up the best fight I think but Mayweather (as much of a ***** that he is) is simply on a different level from the rest of the world, the best boxer since Pernell Whitaker probably.
Depending on the ref, they all beat him. Serg and Pac beat him no matter the ref, and if all rules were thrown out the window, elbowing, HBing, ducking below the waist etc, let Margs were his cement wraps and he'd beat Phonymay. But realistically, all of em could take him depending on how badly he is allowed to cheat.
Thats the stupidest thing I`ve read today (no offence) A guy that defends punches with his face & slow as a snail all wrong for a guy thats the most accurate puncher in the sport, best counter-puncher, arguably the fastest puncher & best defense ? I`d bet my life that you are wrong here, Margarito would badly struggle to win a round in this fight... its Mayweather thats all wrong for Margarito not the other way around.
You're right, that's why Rios is so unsuccessful against the counterpuncher's he's faced. James Toney is arguably the best counterpuncher in the sport, yet he still lost to Sam Peter who has far less skills than Margarito. Sometimes size and toughness can overcome an opponents skill, ESPECIALLY if they can't hurt you.
Martinez has the best chance of winning, then pac then khan. Khan has the best chance of even getting the fight.