Juan "Fenix" Ruiz. I've spoken about him at length on here. Maybe the best p4p chin of the last 20-30 years.
(afaik, never down once in 344 rounds - and fought almost exclusively as the B-side against prospects...even held a few to an occasional MD or SD)
George "Scrap Iron" Johnson. George Foreman on who had the best chin - "I hit him so often that I damaged my hands in that fight. He had taken “Smokin” Joe Frazier the distance and had the best chin I’d ever come across. They stopped the fight but I couldn’t get him out of there cleanly. I still haven’t knocked him out (laughs)."
Randy Smith (29-33-1) 0 KO losses Angel Robinson Garcia (138-79-21) Only 3 stoppage losses all by cuts
Describing an iron-jawed fighter or at least one who has well above average punch resistance as ''low class'' is like describing someone who has just bought a brand new Rolls Royce as owning an old banger A good chin is the #1 physical attribute any fighter can be blessed with and everything else is secondary Glass-jawed fighters are vermin