I think EU2 is quite a bit less complicated than the HOI games....
HoI has a non-colossal learning curve? huh?
I'm a longtime Victoria player, and I still can't figure out how to play HoI. Odd.
EU3. A much more polished game at this point, with a third xpack on the way, and set in the greatest era of human history. Also: renaming your territories FTW.
Civ4 BTS, for the replay value...
Two words.....
GET BOTH!!!!!