Common sense says Aldridge. Skilled big men are hard to come by. If they draft LaMarcus, they will actually have 3 skilled big men.
It's on those guys, however, to play some defense. If they do that, game over. The Raptors now have adequate management (in Colangelo) and should have a great young core after this draft.
My vote: Aldridge or trade involving an established, All-Star caliber veteran.