I've played as: Romani, Karthadastim, Epeiros, Makedonia, Koinon Hellenon and Arche Seleukeia. I've only completed the Makedonia campaign though.

I only play with these factions because I have a great historical interest in them. I know their history, the people who led the factions and the way their units work. I hardly know anything about any of the barbarian factions, that's why I think I never play with them.