the luso army is pretty much the best in the game, for me anyway.

out of the experimenting i've done, their cheaper units beat more expensive units virtually every time.

i shredded gestaesae, pedites, phalanxes and had a few units of cataphract charge head on into light spear and they were halved in no time.

added to this the access to the falxmen and you one hell of an army.