Which creatures from the alternative upgrade options do you choose?

no, it's not ideal, because, as far as I remember, they don't protect others, and if they do, there are still other units besides them.

enough has already been said about the Archdemon, and every time someone asks about the use of his ability, I have to explain it again...
for the final stage, perhaps the first upgrade is good if the entire army is wiped out, but in all other cases, it's an alternative.

I don't know how useful this is in practice; firstly, you can only do this on the 2nd turn, i.e., they will have already had at least one chance to hit us hard; secondly, you can charm/blind the archers, or finally, attack with hounds through their protection.

but this way, they won't be able to hit us hard on the second, third, and subsequent turns.
I don't see the point in charming the archers; it's much better to charm the units protecting them, such as Ogres or Paladins, or other nonsense.
...in any case, you can, again, say that spending the spell on archers is stupid; it's better to charm/blind that very "dangerous unit," isn't it?:)
and don't forget that Devils are not Cyclops; often, it's not that easy to eliminate someone dangerous with them, especially in one go.