IMO, the single most important factor is absolute functional reliability in your pistol. The only way this can be established is by DIY testing. A widely accepted Rule of Thumb is at least 200 rds with zero malfs before any given load should be considered trustworthy for SD use.
Given the technological advances in projectile design and fabrication we have now it's tough to find a premium purpose-made defensive bullet from the major ammo makers which won't expand reliably under most circumstances. As was said, there are no "magic" bullets, but given proper placement the stuff we have now is the most effective we've ever had in any handgun ammo regardless of caliber.
While I'm a follower of the "Bigger Holes and More Mass are Better" school of thought I'm not a fanatic about it. If it turns out that a 165 or 185 gr. load is markedly more accurate or just makes it easier for me to make multiple hits faster and with consistently better precision than with a 200-230 gr. in a given weapon it goes to the front of the line, generally speaking.
Again just MO, but having POA and POI coincide is next. Once you pick a load I'd strongly suggest that taking whatever steps may be needed to regulate the sights on your weapon to do that for you at the distance you consider optimum be a high priority task.
Buy a box each of a couple of your candidates. See if one works better in your pistol. If they both give 100% reliable function, use whichever is more accurate. If that's a toss-up, pick the one that's easiest to get in your area.
As you gain experience and familiarity with your pistol you'll likely develop some personal criteria for defining what's best for you. Trying different brands and loads as money and time allow is the best way I know of to find out what that is.
