For me, it's simple here. No matter the situation, no matter the tactics I use, no matter how developed my hero is, no matter which race I play, I would gladly trade any level 5 creature for the corresponding number of Archliches. Except for Nightmares. In the hands of a demon, with a certain hero development and considering the increased growth, they can be VERY helpful (or not). Archlich is head and shoulders above all others.

Added after 42 seconds
Give the Archlich a level of five and a half!!!