[General Tacticus]

Take an Archdevil, give him 75 devil to lead (that's its limit), and just watch your flying army from hell tear into just about anything. Making your archdevil a SC is just icing on the cake at that point. Can't do that with an Ice devil. On the other hand, my Ice devil is leading my amphibious cross-breeding experiments right now in the South Atlantic, so it too has its place.

So far, the only army which stopped me (long enough for reinforcement to arrive, due to the losses taken) was a Tien Ch'i army with about 350 units total, mostly shades, undead horsemen, and some Behemoth and celestial soldiers. I was fighting at a 1 against 5 numerical disadvantage, and I still won, but lost half my devils... No problem, I am making 15 a turn with soul contracts.

Also, one of the Archdevil has a very nice weapon built in (some kind of scythe).

But there is something better than an Archdevil for this : a demon lord. I have just summoned Pazuzu, no time to equip him yet, and he looks very nice...