Nah, not Hunt. People overstate the Crocop kick. Crocop is not a robot programmed to kick a kickbag with the exact same leverage, energy, technique and precision every time. He is a human being who is in constantly fluctuating state of consciousness, emotion, pain, energy (because he is fighting), and is moving while trying to hit a moving target - thus there is no way of knowing if the kick he hit Hunt with was as hard or as well-aimed as the kicks which took out Igor or Wandy or whoever. Basing a massively comprehensive decision such as best chin ever on ONE SINGLE STRIKE is insanely reductive. There are far, far, far too many intangibles to consider.
I really don't know what the right answer to this question is, it's so difficult. I know I've never been as consistently impressed by a guy's chin as I was all through Nelson's fight with Werdum when Roy kept eating flush knees to the face from a massive guy who was throwing them with good MT technique. But, Nelson has been properly knocked out while Hendo hasn't, and Hendo has been fighting the best guys for so, so long, and occasionally taking a lot of punishment.
I think I have to go with Henderson, but I think age may have chipped away at his resistance to the point where he could get worn down and TKO'd by someone like Bones Jones sometime soon, because Dan is no longer cut out for these five round fights. But at his best, he was true iron.