Which creatures from the alternative upgrade options do you choose?

Well, regarding upgrading, it depends on how lucky you are with resources and those who guard them. I usually upgrade them quite quickly. And they can cast spells quite successfully, even while invisible, and then finish off those who get close. Although, at distances closer than half the map, the Mistresses are definitely more useful. But if the enemy gets close to them, it will be bad, while the Mistresses can at least defend themselves with full force.