Locche is the best purely from a defensive standpoint. Then Whitaker and Pep. I'd have Canto and Zapata as the other two. Canto was tiny and at the type of disadvantage the others and guys like Benitez and Mayweather rarely, if ever, had to endure imo. In a very strong era too. Zapata had an average chin and poor mental focus and drive which hindered him, but his reflexes, range of defensive techniques and eccentric style were better and more expansive than the likes of Mayweather imo even if the latter was probably a better all round fighter.
Calderon might deserve top 10. If not, top 15. You gotta understand, Calderon had nowhere near the natural ability of a Locche, Whitaker, Zapata, ect. The fact that was a defensive wiz on pure craft deserves credit.
You think, X? Dunno man, I've never been high on him myself outside of considerable respect for him being so tiny in an age of weight draining giants and cheats. Quick and good on his feet mostly, ok reflexes but a bit loose/naive and without a real elite grasp over most of the more advanced defensive aspects that a fellow midget like Canto had a proper handle on. And Canto was offensively sharp despite being a light puncher, something else I never thought the wee iron boy really had despite throwing quite a lot of punches. Hmmm. Maybe I'm harsh on him.
Nicolino Locche Willie Pep Pernell Whitaker Floyd Mayweather Jr Wilfred Benitez Honorable mentions: Hilario Zapata Miguel Canto Miguel Lora Marlon Starling Ivan Calderon Sumbu Kalambay James Toney
That honourable mentions group is good, Flo (other than Iron Boy). I'd have the likes of Duran, Benton, Graham, Laguna, Marcel, RJJ, Benny L, Driscoll, Midget Wolgast, Famechon, Loughran, prime Napoles etc in it. Maybe the likes of Mamby, Fourie, Rose and Lomachenko could scrape in. A dark horse for the upper tier based on a limited sample in terms of pure defensive ability before he quickly burnt out due his lifestyle would be Payakaroon imo. He used his height and great footwork a lot but was a formidable defensive talent. Young Griffo too, though we don't have the footage. Ibarra, Pinder and prime Alfonso Lopez were all defensively excellent but had durability and focus issues.
Spinks had some very nice defensive manoeuvres but he still got hit quite a lot. I don't think he belongs on these lists as even an honourable mention. Qawi's defence was better IMO.
One thing that Spinks did really well which I like, that not enough fighters do, was dipping his body and head a wee bit to the right when he jabbed. Very hard to then catch cleanly with straight rights, counter jabs etc and in a position himseld to quickly fire back.