As an LEO I wear mine in front on the off side (left side, since I am right handed)parallel to the gun belt but with the mag openings to the left, for a simple reason. In case I need to go prone, I can still gain easy access to my mags. If they are on the right side (or gun side) and I am prone, I cannot reach them to reload, as I am laying on top of them.
My prone style is not the police prone style (on stomach with heels together) but the rollover prone style which is more stable and allows for better breathing and better cover.
My mags are inserted into the mag holder with the mag butt to the left and bullet side to the ground.