Best skilled creature.

The Kirin is weak, and its trail has never been useful to me. So, I disagree.
The Cyclops isn't that strong in ranged attacks for a level 7 creature, and its toughness rarely comes in handy – it's usually attacked last.
The Angel heals – that's a plus, but it's almost useless in battle. Too weak.
But I think the most useful ones are the Lords and the Archers. The former are powerful, fast, and deal damage in every sense, and the latter simply shoot a lot (although the transformation into archers only happens at the end of the turn, but that's still good).

I'll vote for the Archers, because I rarely send the 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.