If you mean prime for prime I have to go with DM, probably by KO/TKO DM wasn't afraid to take a punch in order to land one of his own, and this should work against someone with average (for a champion) chin and defence. If the fight goes to scorecards Calzaghe may get the decision, especially as DM was often slow starter, but still I would rather bet on Dariusz.
Again - average chin? Too many people judging Calzaghe on Hopkins / Jones - if you do that then judge DM on Fabrice Tiozzo. DM way, way too slow to be competitive