I forgot who said it, but someone here said that Roberto Duran has the greatest accomplishments of a fighter in the last 30 years or so. And I have to agree. For Floyd to be best ever, just ask yourself if he's accomplished more than Roberto Duran (a modern all time great) even if he beats Mosley and Mayweather.

My answer would be no, and Duran is a top 5 fighter of all time by many boxing publications and fans.

I may not even see someone being better than DUran in terms of skills, accomplishments and longevity in my lifetime.