The Cyclops isn't that strong in ranged attacks for a level 7 creature, and his charge ability rarely comes in handy – he's usually attacked last.
The Angel heals, which is a plus, but he's almost useless in battle. He's too weak.
However, I think Lords and Archers are the most useful. The former are powerful, fast, and deal damage in every sense of the word, and the latter simply shoot incredibly well (although the transformation into archers only happens at the end of the turn, but that's still a good thing).
I'll vote for the Archers, because I rarely send Lords into the thick of the enemy (because I don't want to lose them), trying to win without losses, so they mostly hang out in semi-defense.