Who is Best Empire leader for DS TB

I finished 4/4 with Zader leading Darth Nihilus, Palpatine, Darth Maul, and Savage Opress. Forgot about the AT-AT special attack.

I finished 4/4 with Thrawn leading Snowtrooper, TIE Pilot, Royal Guard, and Grand Moff Tarkin. Once again, I forgot about the AT-AT attack.

I finished 3/4 with a First Order team.