EUIII Complete is nothing compared to HttT or DW, and when it comes to mods... (like i play Vicky 2 only with mods)
HttT = Magna Mundi = a mod that makes the game really realistic, adds things like religious minorities, among other things, considered the best EUIII mod and is going to become a game soon
DW = MEIOU = a improving mod that is really good, also will add minorities (it seems like it gave some problems to the mod, so i think they removed it for now) and improve the game overall, with HYW mechanics for example. the cultures are also improved (occitania!)
alternatives are the awesome DAO mod, that improves the game a lot, balances the Ottomans and Russians, and also removed the horde mechanics to (again) allow the Ottomans and Russians to get hyper-strong.
or Miscmods, it REALLY IMPROVES THE COLONIES, it adds specific colonial revolters for the Asians and even muslims, it has some Alternative history scenarios and improves a bunch of other things.