I'm very surprised a non-heroic sith guild is doing Geo TB! But I guess these are the times we live in now. For sith raid, Resistance is the simplest for P1 damage, but you don't seem to have JTR unlocked, and you need her leader ability.
What are you currently using in P2?
I think Nightsisters are still the best powerhouse for P3 and P4 (maybe clones now, not sure). If you want to maximize your raid damage then that's where I'd go, but you're behind on stars for a lot of them. Also, you'll need to go to YouTube/forums/Reddit for strategies to make sure about mods and stuff. Unfortunately I'm not huge on the raids, I usually miss them most of the time because my guild raids around my bedtime, so I'm not the best for raid advice.