Sweet Pea, but it's very close. The consensus top 3 are the two names in this thread and Locche. Locche is #1 though.
I would go Mayweather. Whitaker was sick too. I only go Mayweather because he used to dodge and block while Whitaker used to just dodge which, only once in awhile, had him with swollen eyes.
Whitaker, clearly. Both are great defensive boxers, but anyone who says it is close cannot have seen the Fantastic Five of Sweet Pea's fights: Ramirez II, Nelson, Chavez, McGirt I, Haugen. Whitaker was the superior defensive boxer without a doubt IMO.
I went with Whitaker just becuase I prefer his defensive style more, hard to choose whos actually better.
My Man Sweet Pea to be sure. That cat was a defensive genius...especially in his later years when he wouldn't move as much but could still be almost impossible to hit cleanly.
Whitaker. Other defensive masters that are easily on his level to look into are Nicolino Locche and Miguel Canto.
Generally regarded as the best pure boxer ever. The problem is that there really isn't any film of him in his absolute prime years, but what we do have footage of is easily enough to rank him right alongside anyone else for defensive mastery.
Both of those guys are in the top 10 but you can put Robinson up there because in his prime he was great at everything. Hopkins and Ali should be mentioned as well as Ray Leonard (Post 1980).