9 mm gun, what to get?

Honestly, it really doesn't matter what one you buy. Other than a couple of brands, all are pretty good quality and should serve you well. Just stick with a 9mm or above for defensive purposes, make sure it is comfortable in your hand, practice, practice, practice, and take a good Handgun 1 class. Take more classes as time and money allow. BTW, when practicing, don't just put rounds down range. Actually work on your technique and not learn bad habits. An old saying I live by when it comes to practice/training...

Train like you fight, fight like you train.
In a stressful shooting situation you WILL revert to your training so train the right way from the start!