I'm a big Camacho advocate on this site but you've got a tough sell on your hands if you're saying he's got the best chin ever. He certainly had a top 5 atg chin at 135 and 140 (he was so good at 130, it was never tested) but I think part of his "granite chin" reputation comes from his feet and the inability of his opponents to hit him flush(with the notable exceptions of Rosario, Chavez and Trinidad).
H2H : McCall , Chuvalo , Tua , Toney P4P : Toney , maybe McCall also , Hagler , Jorge Castro , Reggie Johnson , Hector Camacho , Ray Leonard , Duran , Carmen Basilio , Ray Leonard , Sam Langford
Not that proven as he never faced Tua , McCall or a Klitschko. He was down again Toney , Cooper and Bowe and stopped by Toney and Bowe. I heard he was down against Ruiz also . Maybe I forgot others. I have also seen him hurt on more occasions than these. Still I would say his chin is above the average in both strength and the amount of testing it went through , but not one of the top 5 in neither P4P nor H2H.
I've seen fights stopped for less than the beating Muhammad Ali was taking from Frazier. He ain't got the best chin ever and neither is it anywhere close - do you really think Ali could take the same kind of punishment that LaMotta took off Robinson? Or even Napoles from Monzon?
So, you think a fighter who was never KOed in 299 fights despite fighting from mw to hw should not be mentioned when it comes to great chins? You are a f*cking ******, Pachilles.