Wayne McCullough has to be up there. Fought some very good punchers, not even getting wobbled along the way. And the Larios fight was just sick, he was taking unanswered punches, clean to his face and when the doctor stepped in, he was begging her to let him continue, she was apologising and saying she had to stop it, quite upsetting really.
Ali got up after being knocked down. Many of the other NEVER even went down! Chuvalo, LaMotta, Arrington, Hagler etc. Ibar Arrington fought guys like Holmes and Coetzee and would drop his hands and taunt and let the opponent hit him flush and then laugh and hit himself with no effect from any of it. Now that is a chin!