About regular and alternative upgrades.

Well, that's subjective, but okay. 1. Hunters. Forget about ranged attacks; they are useless for a Tier 1 unit with their penalties, and melee units are better among the hunters; I won’t even mention invisibility. 2. Furies – they are faster. 3. Minotaur Guard is preferable. The Cleaver is quite powerful. Although in some cases you can take Overseers if morale is critical. 4. Dark Riders: ignoring defense is a very serious ability. Unfortunately, you cannot significantly damage the enemy army with an attack "on the way." 5. Cave Hydras because of regeneration. 6. Night Hags: forget about ranged attacks. Unless you are playing as Erinn, of course. Though we could argue here; I don't know. In some ways, losing your only decent archer might not be wise... But invisibility is great; you can't forget that it's strong. 7. It depends on the situation. Generally, immunity to black dragon magic is not always needed. But often it is, especially if your opponent has a chance to use Darkness or something similar. And generally, red ones will be stronger. P.S. I will merge this topic with this one if there are no objections.