Need some advice: I have currently 4 Zetas left and losing my current GAC

Maul is sort of dead weight on a Palp squad, but if you have some other sith knocking around, Maul's zeta makes for a pretty awesome sith b-team, and you only need the one zeta.

In any case, if you're struggling and have 4 zeta upgrades available, I'd try to spread them out to make two or three teams work rather than load them all into one squad. Good candidates would be both Shaak Ti and Brood Alpha. Both those teams will hit way above their weight at low gear levels.