I have to go with PBF because of style. He's in Pernell Whitaker and Benny Leonard territory: defensive genius' who are almost impossible to look good against.

Its possible at age 32 PBF has slowed a bit, and that split second in reflex can transform a fighter from unbeatable to mortal, as RJJ discovered rather quickly.

But short of that, PBF is one of those rare defense-first fighters who remain complete enigma's in their prime: impossible puzzles to solve.