It is matter of personal preference. Lots of good answers here. I'm a Hornady, RIP and Gold Dot fan myself.

Ruger ARX 80grain. They punch well above their weight. They easily penetrate denim and clothes, fragment well inside the cavity and you won't risk over penetration. They create massive wound cavitations. You can watch ARX ammos performance on YouTube.

We always recommend that you find out what the cops in your area use so if, God forbid, you must shoot someone you can use the fact that police use the same ammo in your defense. Here it's Federal Hydra-shoks 147 grain which will run well in the Glock.

I'm a fan of the Hornady critical defense. I use it in various calibers. Always performs well.

Personally I'm a big fan of Federal HSTs. They aren't super expensive, tend to cycle well in everything, and all the testing suggests that they expand reliably.

You've asked a very opinionated question. Some folks like one brand over another. Basically you can select any of the well known brands that have hollow points. Here are some well known choices for defensive ammo: Federal Premium LE HST, Speer® GOLD DOT, Winchester PDX1 DEFENDER, Hornady Critical DUTY, and Remington GOLDEN SABER. Do a Google search for "best 9mm ammo" or best 9mm defensive ammo" and you'll come up with hundreds of sites with varied opinions. For myself, I keep Hornady Critical Duty in my 9mm Walther PPS M2 and keep Hornady Critical Defense in my Walther PPQ 45.