McCallum is tough and close a sd/md type of decision but I lean towards Hops (no shock, huh) Outside of Nunn/Kalambay (who I also think he beats ) he runs the rest of the table without to much trouble
He might have some difficult moments early due to Roldan's awkwardness, but he would soon settle in and make it into more or less a beat down before the stoppage came, I think. You have to bring more than power and a rugged awkwardness to the table to trouble Hopkins, at his best, for a whole fight.
Kalambay and McCallum are probably the ones with the best chance here, the more I think about it. They had no obvious flaw that Hopkins could exploit. Nunn never impressed me over 12. He was slowing down noticeably against Toney already after 6 rds. Late 90's Hopkins could keep high pressure on for a full fight no problem and would make it dirty and messy. I just don't see Nunn coping too well with this. Hearns was susceptible to getting caught as the fight wore on. He looked good against exactly one high level MW, and that was through a first rd KO, something which isn't very likely here. He certainly could hurt Hopkins and make it a very tough night for him, but I wonder if Bernard doesn't find a way to get him out of there.
Hopkins did things that in theory should give him trouble against good counter punchers. It was mostly that he went too low with his head often, when ducking for example, and overbalanced at times when attacking, especially with his lead right. He very rarely got punished for this (Kovalev countered and dropped Hopkins when he overbalanced, but he was ancient then), probably because he had such good anticipation that he almost always managed to get a clinch and some mauling done from really being out of position. But it would be interesting to see how fighters of the calibre of Hearns, Nunn and especially classic counter punchers like Kalambay and McCallum could potentially exploit these tendencies.