Tree of Life + Gaia Start.

Lost Colony + Void Dwellers? I quite like the idea of a mega-corporation that has disconnected from their origin empire's planet into a space habitat that they govern.

Mechanist + Syncretic Evo

Post-Apoc + Lost Colony (The choice was to settle the blasted wasteland or die of starvation in space, have bonus to Tomb Habitability but regular hab otherwise)

Lost Colony + Syncretic Evo (They found a world to settle on but it had xenos already on it, they settled anyway)

Fed/Heg start + Voidborne/Gaia start (just OP really)

Scion + Post-Apoc/Gaia start

Mechanist + Gaia start

Mechanist plus post apoc? Was my favorite start in older Stellaris haha