Anti Man for the MRUT.
For uniforms I would say QS and Iron Man are a definite yes. The top ones I would suggest out of the ones you mentioned would be Hulkbuster, Wasp (for TL), RR, War Machine, and Black Widow.
Groot GOTG2 if you need some heals in WB. Satana isn't bad.Ghost Rider just isn't that good. You should wait for Rogue to get a new one soon. Finish QS now and don't worry about SW/Thanos/BO. Mordo is very bad with the uniform. Silk is pretty OK. Ant-Man doesn't have stellar DPS but has great survivability. Star-Lord just has lots of iFrames, a leadership, and not terrible DPS. Elsa's MU uniform is a massive increase from the base.