Prime for prime, Hopkins. But he's 43. His reflexes have slowed and your ability to absorb punishment diminishes as you age: so, Margarito. But it's real close. I'd include Andrade on this poll as well. He has a head like a brick.
He has a very good chin for sure but he takes so many punches and he got floored by Mack. I won't be shocked if Bute stops him. I would be surprised if he will be knocked out, but not shocked.
Vitali. Margarito has been hurt, Hopkins was down. Vitali never looked even stunned. What a shocked it would be to see him taking just a standing 8 count. But that's never going to happen. Therefore my vote goes to Vitali. It would be a shocker.
The thing is, he fights at a weight where every big punch can be a knockout. Besides, Sanders did hurt him in the early rounds. He has a great chin for sure, but I don't think Margarito was ever hurt more than Vitali was against Sanders. The two knockdowns Nard suffered were in an outdoor fight at Equador. There is a high altitude there, and it's very difficult to breath (my brother was there and told me). I'm pretty sure it had a lot to do with that, but Bernard is man enough to never mention those conditions and offer an excuse.