Anytime I've ever changed the roll at a friend's house or as a kid I've always used the over orientation, though as of now I have to keep my toilet paper in the closet and grab a roll as needed because one of my cats seems to think TP is a world class delicacy... The under orientation just looks so off to me, and I actually remember a few times when I've been at the gym and I've flipped the roll because it was "backwards".
I could care less. When I was younger, one of my parents preferred over, but the other wanted under. So whenever I used the bathroom it seemed to change every time.