Gavilan is tough for me because of several fights I've read he had robbed from him, yet I've never been able to see them and draw my own conclusions.
Leonard - best on film, best resume Galivan - arguably beat a prime Robinson Napoles - he doesnt look as great skill wise and his WW resume isnt as strong, although remember he was at the LW limit till about 28
Armando Muniz who fought both said Napoloes was better than Leonard, when asked are you sure he said oh yes definitely! The Video is on you tube under "Muniz talks on Pac,cotto,Arreola,Klitchko. However my ATG list looks like this Leonard' Napoloes - Gavilan i have a hard time seperating these 2.
I'd put Leonard at the top based on his all around abilities, combined with the fact that he proved himself against 4 of the best fighters of all time and the best of the era, 3 of them at Welterweight. Next in line would be Napoles based on his skill-set and dominance at the weight despite not even being natural there. Obviously Gavilan would come next, though there's really not much between any of these 3. Hardly a disparity in class or anything.
It's just about who you like the most. You could have these gusy in any order and I wouldn't argue about it. Throw in Griffith too... All of them are elite fighters.
Gavilan at 2 (as impressive on film as any fighter I've seen) Leonard at 3-Has thosewins over Duran, Benitez and Hearns. Napoles at 4: Win over Griffith-Damn impressive. Haven't watched the 2nd Cokes fight yet but Napoles is punch perfect in the first, his head movement/foot movement absolutely mind blowing, precise and calculated, the shots flowing naturally. His resume isn't mind blowing at 147, but considering why he went to the division in the first place and his consistency (bar cuts) I rank Napoles very high at the weight. :good
Gavilan and Leonard may have had more aesthetic styles (Gavilan was one of the first old-school champions to become a TV favourite and trigger the trend towards the "TV fighters" of the mid-late 50s. And Leonard of course was TV gold) ........... but I think Napoles was the greater fighter.