Buy the one you can shoot the most accurately.
This. A gun is worthless if you can't hit a target. Most of the time, a gun will probably scare the person off. However, if you find you must pull the trigger, you're probably in a situation where missing is going to be a very bad thing. You mentioned going to a range to try some out. That is a smart plan. Shoot as many rounds out of as many guns as you can to get a feel for what would be best in your hands.