Scipii got a good unit roster, although they are the "hardest" Roman faction to play. The Carthaginians arent that much of a threat, but the cities the Scipii take have high cultural penalty and squalor.

But Corvus Quinquireme & Decere are awesome ships.

Seleucids have a good selection of troops, although I would like to mention Pontus too.

They got Eastern Infantry, which I use early as fodder, and then Phalanx Pikemen who when used correctly are devastating. Their elite infantry is the Bronze Shields, who are easily the peers of Silver Shield Pikemen. Otherwise they can also recruit Thracians, Cretan Archers, Sarmatian mercs and Rhodian Slingers.

Their cavalry selection is also impressive. Scythed Chariots and Chariot Archers for instance.
Pontic light cavalry arent that great as they got javelins, and suck at melee. But they are fast, and is perfect for pursuits.
Pontic Heavy Cavalry is also armed with javelins, but they got good enough melee stats, and can rout light infantry.
A large city (12.000) with the tech level stables can train Cappadocian cavalry, who are just as good as Cataphracts.