I agree Sayword. Hagler was a bad, bad man. But Hopkins is being seriously under-rated by the brothers in this room. This fight would be a pick-em, and I can't see anyone knocking Hopkins out. Hopkins has it all, he can box + he has a vicous inside game. He isn't a devasting puncher, but he can knock you out, and is relentless.
As far as the great Sugar Ray Robinson is concerned, he was at his best at Welterweight. As a Middleweight the original Sugar Ray had quite a few losses to not so great fighters (Randy Turpin, Gene Fullmer, Carmen Basillo). As a result I wouldn't automatically give him a victor over Hagler or Hopkins. I think both would give him all he could handle, an both could beat him.
P.S. Ray Mancini was a lightweight, not a middleweight.