I think it depends on what you listen to for music. If you like a heavy metal, then id go for two 10's in a sealed enclosure. The sealed will not be quite as efficient as a ported box, but the bass kicks will be tighter and the 10" subs will have a slightly faster response curve.
If you listen to rap, then youll be great with a couple 12's in a ported box. The ported box will use the amps power more efficiently and produce some nice booming bass notes for ya.
Personally I think peeps get a little carried away with the "my amp is bigger than yours" shit. As long as I can cruise down the highway with my windows down, and not be able to really hear all the fucking motorcycles, then im good, and dont really need any more than that.