My son's close friend, an accomplished half-pipe snowboarder, has very peculiar stance preferences in that if the board has bindings (e.g. snowboard, wakeboard), he rides regular; if the board doesn't have bindings (e.g. skateboard, wake surf), he rides goofy. That is really goofy!
Me... I started skateboarding at the age of 5 in 1966 on a "Hang Ten" board with metal wheels. None of us kids knew what to do other than what felt right. Left foot forward was what felt most comfortable, but I have been cursed with pushing Mongo ever since. Though I have learned to push with my right leg, I can push with more power using the left. Even though I am right foot/hand dominant.