Against which factions is it easier for demons to fight, and against which is it more difficult?

I still believe that demons have the most difficulty against elves. Especially when led by Wing and benefiting from elven luck, demons are practically helpless. That's where the imbalance lies. The second problem for demons seems to be Necropolis (darkness doesn't work well against them). And in third place are the Academy, which has a lot of mana, and three units that are immune to mind control spells (Titans, of course, are the main ones). Demons also don't have much to offer against Fortress.