Recommended faction?

[Trithemius]

On topic: The Romani are great!

• Neat units - Roman units are quite fun, the early formations (h/p/t + light troops) give you a lot of variety in forming your line and you can take a historical recreation approach to your battle-plans, or just freely experiment. The current lack of dedicated auxiliaries to be recruited can be easily dealt with by recruiting Gallic or Hellenistic skirmisher, archer, and light cavalry and infantry units.
• Triumphs, and other trait-stuff - I think the Roman submissions are really excellent since they have been a real inspiration for me to move outside my strategic "comfort zone" in order to make my leading commanders into heroic personalities. I think they also give an interesting glimpse of some rather fascinating aspects of Roman society; the same is true, to a lesser extent, of the cursus honorum and the various corona.
• Challenging strategic situation - Rome is situated in the middle, and has a lot of options about where to go and what to do. A would-be imperator can concentrate on Gaul, or Illyria, or take sea voyages to despoil Greece or Carthage or Iberia. The way Roman legions are recruited also presents its own problems (i.e. challenges, i.e. fun!).

Going the Romani is a great choice, I think.

[pezhetairoi]

I agree, now that my Romani campaign is in full speed ahead. You're always forced to return to the motherland before the coming of Marius to retrain or replenish, and that makes long-distance campaigns ever that difficult and challenging since there's always the chance of a counterattack from the enemy.