Vitali Klitschko might deserve more credit for his chin. Whatever some think of him overall (I am a fan, but know some aren't), his chin is mighty impressive.
And Gavilan, Chavez and Duran? Gavilan was never ko in a 100+ fights and I think he only visited the mat once,
1.) That was an exhibition on iron.. as in iron jaw. 2.) 'Ref should have stopped that sooner. 3.) Robinson makes Floyd, the self-professed GOAT, look stiff.
I'm not sure how you can have a current top chins list and not include Glen Johnson. He's only been wobbled once in his career as far as I know, and that was as a 41 year old against Tavoris Cloud.
Also, both Tua and McCall were down in their last fights. Valuev also got hurt pretty bad against Haye. I don't think Valuev's chin is that great as much as that he's 7'0" tall, so most fighters can't properly turn their hips into a punch when hitting him in the head.