Serendipity
Explorer
Class. Both because they have stated they'll include every class in each PH and because of established granularity - both the combat cleric and the paladin are going to be their own class, even though both are holy warriors that cast spells, turn undead, and wear full armor in combat. The differences are one of degree and emphasis, and so far that's it. If that's the level of class distinction being shown in the core, then give me both rogues and assassins.