Which units would you replace in the Dark Elf faction?

You're saying that Minotaurs should be replaced. But where would they go? Think for yourselves: where can Minotaurs live? (not necessarily in the HOMM V setting) I personally doubt they belong on a lawn. Just grazing peacefully... nibbling grass... it's absurd! Originally, Minotaurs lived in caves, or more precisely (as has been imagined) in labyrinths. By the way, in all parts of "Heroes", Minotaurs lived exactly in the labyrinth. The castles were simply not called Dungeon, but Warlock. That is, named after the wizard. In my opinion, removing units that have survived all five parts of the series from the game is, to say the least, foolish. But that's just my personal opinion.
In general, I suggest replacing the Matriarch with, say, Manticores. Their only advantage is that they shoot and cast Slow.
P.S. Dungeon itself is a very strong castle, and it is logical that besides "super" monsters, there should also be weak ones. That's what the fragile word "balance" is for.