Is empire good? I have both Rome and Medieval II, but I didn't get Empire because there were a lot of comments saying that Steam made it really hard to access and troublesome.
Anyway, I love the series, it's brilliant, had a lot of fun playing it... Recently played it again, but as France, in about 200 turns I smashed Holy Rome, defeated England and Scotland, took over the Papal States, and started some wars with Denmark, Venice and Milan. Good times, French cavalry is really powerful.
And on Rome Total war it's fun to play as Greece, since the Spartans are so overpowered and own everything.