Floyd is a defensive maestro whether or not you like his silly negotiating table tactics. He made Canelo, an overrated but still very good fighter, look extremely lost.
Prime Roy back in his day made you think he had excellent defense because he was so hard to hit . Yet it was really excellent reflexes that saved him .
chavez, early in his career had very subtle defense. oscar couldn't get out of the way of a right hand. i wouldn't call his defense good. whitaker was a defensive wizard. floyd, hands down...has thee best defense. james toney deserves mention. bhops defense is excellent. rigondeaux has very good defense. so does lara and trout.
Floyd, followed by Rigo, and whoever else. And for those who are going to say "Rigo got dropped by Donaire", that has more to do with his chin than his defense. FLoyd, then Rigo,