Now that I've downloaded EB, I've got to say that EB is the most fun to play. It's not just a mindless rush to build masses of units and conquer like vanilla, with the rebels not only being a little better, but often even more of a challenge to conquer than the main factions! (Over a full stack in most rebellious cities) The fun factions would probably be the more completed ones at the moment, such as the Greeks with their special touches (Olympic games and Greek UI, and a decent amount of units) and challenging starting position, the Romans (not playing them yet though, don't like having the Greek Romans).