Left, now before everyone starts saying 'add this fighter, add that fighter... No this fighter? Got a lighter?' I will say that my list contains examples and examples only, and is not meant to be complete and comprehensive.
A couple more: Chavez ,before he was washed up he walked through a lot of big bombs. How bout Camacho, 85 fights no KO losses, great survival skills.
Not really one of my favorites, but i think Bernard Hopkins deserves a mention. He has not been tested that well, but i believe he has only been down two times which is impressive nonetheless. It was surely impressive to see him take those bombs from Jones, who is a huge puncher at 160/168, without being hurt or staggered. Oscar De la Hoya seemed to have a fine chin as well. They're not in the league of a Hagler, LaMotta or Napoles, but outstanding nethertheless.
He's definitely up there. Took a shitload of punishement from an offensively-peak Wladimir Klitschko at the age of 41 before being stopped on his feet after only one knockdown. The knockout against Briggs seemed to be more of a quit job after a punch on the back of the head than a clean knockout.
I will mention the obvious choices and ones that come to mind because I don't feel like thinking a lot right now. George Chuvalo Marvin Hagler Olivar McCall Tex Cobb Jake LaMotta Max Baer Ray Robinson Rocky Marciano James Toney Carmen Basilio Larry Holmes (arguable)
How about David Tua.... surprised its taken this long for him to come up..unless i missed something.. My boy Mosley has a pretty good one, but i dont think it cracks the top 20 p4p list..(all-time)
I think p4p is a bad way to judge chin, it's better to do it with opposition. Otherwise there are few chinners who went up in weight and had solid beards. Like Eubank and Toney, Toney would be first easy.