I choose exo, because I think it makes a flavorful character. If you put the abrahamic religion spin on it, we are the grandchildren of god, and that's just bad ass. The children of men? Come on! Kick ass :P
I also like the idea of being built to protect our creators. It's puts a certain humbling color upon the exo race, and the lowly, tireless, guardian idea is very heroic to me. It actually reminds me a lot of Witchers.