Gallowglasses - With a 0 defense they are too fragile for me. I would have to babysit them the whole game and only use them as a flanking unit only.

Billmen - They seemed to be comparable to Chivalric Foot Knights when upgraded. I just don't like their low starting morale though.

Alans - I need to look into them. They seem very capable as a unit to chase down missle units.