best infantry=urban cohort/bastarnae mercenaries
Those bastardized mercenaries are great!! Whenever i'm losing a battle, and i have nearly no men left except for a unit of bastardized mercenaries or their counterparts, thracian mercs, then they are just great for throwing in there and getting you a phyrric victory. They just carve through the enemy ranks. I once had a 37 man unit of them, and they killed half of a 300 strong rebel army. That is how good they are. They're almost as good as rodeo singers (rhodisian slingers).