Victoria 2 isn't out for another two months so that isn't a consideration to me right now.
To me Rome's the sensible option because of the timing for the others. That said I'll probably get the expansion no matter what game it's for.
If they were to announce an expansion to a game that's not out for months, I'd feel extremely inclined to not get the expansion and go to the forum to gripe bitterly about every freaking bug left in vanilla, 3D clipping issues included.