Sovereign class. Not just looks, but as described in the novels aswell, where (to me) it really comes across as the perfect blend between an explorer and a ship capable of holding its own in a fight.
Second choice is a shared place between Galaxy class and Defiant. Defiant, because it's a tough little ship, nuff said. Galaxy, because it and the Sovereign are alike in so many ways, but the idea of families on starships just bugs me, and some of the interior was just to plushy for me.