I've played them all at least one time. I especially like Bactria. A good mix of soldiers, nice starting position, early blitzing, far superior enemies.
Rome
Carthage
Greek City States
Macedon
Seleucid Empire
Ptolemaic Empire
Baktria
Armenia
Pontus
Saba
Gauls
Germans
Iberians
Thrace
Parthia
Scythia
Massalia
Syracuse
Cyrenaica
Epirus
Pergamon
Bosporan Kingdom
Galatians
I've played them all at least one time. I especially like Bactria. A good mix of soldiers, nice starting position, early blitzing, far superior enemies.