Have u done act 5 100% yet? If not would recommend u do that first as the rewards will help fill out ur roster.
Ill stick to ur 6*'s, would recommend ranking serpent, archangel (preferrably duped with high sig) and BWCV she was prob my mvp for act 6 and 7. Those are the ones id begin with anyway.
I’ve done act 5 50% so far, collector was very annoying. Sounds like some solid advice, I’ll take it on board and see how it goes.