____ _ _
Dungeon takes first place in Offensive Magic (very dangerous at the start).
As for units, their light counterparts (Sylvan) usually take first place.
I'll add that the strength of the Dungeon creatures is compensated by their numbers... (they have the smallest growth rate).
Lastly, and perhaps most importantly, the strength of a faction depends on the hero's development, the opponent, and the player's personal experience.
For example:
...I was defeated by a player playing as mages, but his main hero was a Necromancer!!
---
*Back in the days of v1.0, I also liked the Dungeon.
*The Black Dragon is the strongest creature of level 7... in Ashan, it only has to fear one thing - the Striking Sword of the Hammers of Fate.