Overseer C with Wight is hilarious. On Torment V, enemy crew in the first few sectors are often dead before the Devastator Beam finishes charging.
Fiend is controllable, but can't man or repair, and has no gear slots.
Seduced Mystic has Summon Thrall spell and Chaos Engine tool. Tool instead of chaos warp spell is a bit awkward. It wants you to use to teleport the thrall pit thralls to suicide bomb the enemy, but the Mystic has to go with them and is fragile at 20 hp. You can't immediately recall just the Mystic, as it recalls everyone.
No sensors, and the ship is a pain the vent, so be diligent with patrolling for fires.