Its hard to say... both have similar levels of opposition, both are amazingly fast, but ROy Jones Jr. because of his athleticism could make even the highest level of competition look easy. Technically there hasn't been anyone like Floyd Mayweather jr., but despite the fact he is a great athlete, he isn't the same athlete Roy Jones Jr. was, and there has never been an athlete like Roy Jones Jr. in the sport. If they fought p4p I would vote for Roy Jones Jr. based on what I saw with Mayweather against Oscar. However I believe Mayweather has a run of big fights in the near future. He is in the most skill packed division with nowhere to go, and I think he isn't scared to stay and fight the welterweights. IMO Mayweather has a chance to have a record that will put him in the top 20 p4p of almost anyone, but he still has Mosley, Margarito, Williams, Cotto, maybe later on Berto inbetween him and that stature.