Well I would have suggested the Seleukids comsidering that's what my next faction will be, but if you really don't want to play them then... Rome or Egypt . The Ptolemies are rich, have the greatest city in the game when it starts, posess the body of Alexandros, have quick access to elephants if they choose to move South, and have the great honour of being the only faction the Seleukids fear (at least at the start).

Rome is simply the best faction in the game. Period.