Well first state unit sizes and difficulty settings

Heres the ones I've played and all on huge settings.
A bit of the rules I play by. No bribing except rare cases such as a nice big fat rebel mercanary army. No mass cavalry except if I ever play an eastern faction.

Roman Brutii
Gauls ........ And I thought they'd be hard on huge settings.
Roman scipii
Greek cities
Roman Julii
Selucids ........ annoying surroundings, not many big towns/cities for your choosing but considering a 95 percent chance you'll get to the mercanaries first allows you to get the upper edge on your enemies. After the patch hopefully the A.I. will take a look at mercanaries before making it's move.
Carthage .......... Let me just say I went King Phyrics academy for warfare