Selecuid (excuse spelling) are OK, you need to get offensive fairly fast but once you have taught your neighbours how to behave, they have a good variety of unit types.

Personally I dislike the Romans on historical principle & was a bit miffed I had to play them to access the other factions in the first place, which makes wiping the floor with them using any other faction a bonus.

Also have you considered the RTW realism mod? That opens up the variety of factions available, & balanaces, (depending upon your point of view), certain unit types.