Which alternate upgrade for Inferno do you like the most?

Imps, if I'm going for Pit Lords, and devils if I'm going for Pit Fiends. I think it's clear why: in the first case, it's infinite mana, and in the second, it's a combat-ready unit. Demons are often new, but in some cases, they're old, because the old ones have a ton of defense, while the new ones have almost none. New dogs, because 1 damage doesn't matter, but an attack range of six cells does. When there aren't enough, I make new Succubi to reduce losses when breaking through and so on. When there are about fifty of them, I turn them into Demonesses. I usually make new horses, because the damage bonus is more significant than the minus three to spirit. Spirit isn't that important here anyway. I build different Pit Lords, as I like. I don't get to devils, I defeat everyone even earlier, although leveling up can be useful in a duel or in the final battle, and teleportation can be used to pull my creatures out from under fire. They are equally useful.