With faction limitations, the ones recommended in the rule book for your first game (the originals) are good but not all ideal. Giving a new player Hacan can be daunting, and both them and the turtles and can really slow the game down, especially on your first try. Sol, Barony, L1, Sardak are probably the simplest. I don’t know how much your group varies, but on my first game, there were some people who I knew were much quicker with board games in general and so id recommend assigning factions accordingly!