As a refresher:
Sersi - can transform on substance into another
Sprite - can create illusions
Ikaris - can fly and shoot eye beams of cosmic energy
Ajak - can heal
Kingo - can shoot cosmic energy from his finger tips
Gilgamesh - can create cosmic energy gauntlets
Thena - can create cosmic energy weapons
Druig - can control people's minds
Phastos - can build structures out of cosmic energy as well as 3D holograms of other objects
Makkari - can run super fast
Personally, I'd take Phastos' power. Phastos can build just about anything. He's kind of the best of Thena, Kingo, and Gilgamesh. Though healing and speed are pretty useful too.
