Mine is an Egalitarian, Xenophile, Materialist Technocracy. My guys learned long ago, that it's best to plan ahead and live in harmony with nature and each other. They will terraform all their planets into Gaia worlds, welcome all who wish to be a part of their empire and grant equal rights and utopian abundance (Shared Burdens require Fanatic Egalitarian, too bad). I'm also thinking about vassalizing every other empire on beneficial terms, thus also making them part of my federation.
I do love playing some degree of Spiritualism (ever since Alpha Centauri and the Gaia Stepsisters), the other axis though vary from playthrough to playthrough... or rather per Game since I rarely finished a Game :D
There was an empire I used to try and make in the past when the life seeded mod was updated still that was essentially just like galactic zookeepers. They would seed life on most planets in their borders and just do research and interact with them. It was always hard to make it accurately because they're sort of xenophile as they find aliens interesting but don't exactly treat them equally. So I always struggled with what ethics to make them other then materialist.
Fanatic Xenophile, Materialist, Oligarchic government. The goal is to win economically. I would set the game to have slow growth in general. I would mostly rely on deplomacy to survive eventually build military to a point it would be the strongest in the game. Ideally I would form research federation with a megacorp for sweet tech and migration. For fun I would set my species to be unruly, thrifty and slow learners.