If you haven't played as the Romani, I suggest you try them. They may not be difficult, but their many reforms and their construction options are good reasons to consider them. Besides these things, their elite units (pedites extraordinarii, camillian trairii,...) are really sweet and you get to fight the Aedui, which can be though on the higher difficulty levels.

However: if you're a blitzer, I'd choose a different faction.