Discussion about Sylvan (Wood Elves).

Peasants as a unit are useless on their own. To upgrade them, you need to find money and then upgrade them again, which costs even more money, and by the time you do all that, it's no longer the beginning of the game. Will Dancers defeat Minotaurs? Level 2 against a level 3 tank? The Dancers will take a lot of damage from the counterattack and then the Minotaurs' regular attack will follow. Of course, nothing will remain of the Furies against Archers, but they aren't Archers either, so it's not a fair comparison. Not much will remain of the Dancers either.

The Dancers won't defeat the Minotaurs, but with the defense bonus for moving through a cell, they will hold out well, especially if buffed. I would use the Minotaurs as a distraction while the Archers attack the Furies, and then switch to the Minotaurs with the rest of the units. Besides, there will still be Dryads left, who won't take much damage from the counterattack. Another obstacle for the Minotaurs on their way to the Archers, although a small one.
Regarding the fact that the Undead are cheaper, yes, that's true, but if you consider the ratio of Stronghold units and a couple of additional Necropolis heroes at the beginning for Dark Energy and a certain number of troops, the Stronghold units will pay for themselves much sooner. They will be better at defending mines than the small increase in Dark Energy from two level 6 heroes.