In my only-partially-educated opinion, cartridge choice is not near the top of the list. However, it IS on the list, and it's what you asked. In my less-problematic situation (fewer square feet, less dense population), I have chosen the FBI load. I believe that most or all of the loads eb07 has suggested are reasonable.

A backwards HBWC may not be accurate. That bears testing.

Don't forget the possibility of body armor.