I'm pretty early in the game but I am liking the priests and archmage.
The archmage is immune to those annoying wolf howls and I always use his defense spell on my melee units to cut down on attrition. He does reasonable damage when he uses his trance ability. I've even used the telekenisis ability now and then to push an enemy troop away from my units or towards their units so I can maximize my fireball effectiveness.
And the priests...now that I have some royal snakes I find the priest Bless spell useful as well as their healing spell (since the snakes have enough hp to make it worthwhile). I find that when I have the priests using those spells that frees me up to cast offensive spells on the enemy.
Perhaps when I get a little further I'll rethink this of course
