There are many factors that are "unique" to us as individuals, as such what will work for will be different for each of us.
All I can do is really share my criteria and what works for me may not work for you.
1. A gun is a defensive tool, for me my choice in determining a carry gun will be based on "threat assessment".
2. What is your honest level of competency with your pistol. Yes most gun fights are close, under 3 yards, but for me I want a pistol that I can rapidly engage targets at 7 to 10 yards and be able to deliver aimed body and head shots at ranges up to 15 yards.
3. For me my defensive gun must allow me to engage 3 plus attackers quickly. My definition of quickly is I draw my gun and place 2 shots center mass on 3 targets in under 3 seconds. My goal is to have my fast draw stay consistently under 1.5 seconds.
One second draws are attainable with practice. The average fast reaction time is .75 seconds. If a person can get their concealed draw down to 1 to 1.3 second range, they can get their gun draw and shots fired before your attacker can process that they just got shot.
Overall I am not a fan of revolvers because I can't get rapid follow up shots.
4. My recommended common caliber choices, 9mm, 40 cal, 45 cal. Other options although less common are the 38 super, 357 sig and 10mm. The 9mm is the minimum caliber I would carry.
5. If you are carrying, your gun is not a fashion accessory, it is a tool and instead of getting a gun to go with your outfits, your outfits should be tailored to go with your gun.
6. Consider you may have to have multiple guns because not every gun is suited for everything. There will always be some trade offs, deal with it.
7. Your gun is part of your defense, don't make your personal defense "gun centric" because if you do, if you lose your gun, your become defenseless.
8. Practice to maintain marksmanship skills, train to maintain defense skills. Defensive shooting is different from target shooting. Strongly suggest taking defensive handgun courses.
9. FWIW, I carry a 45 cal. Colt XSE with at least one spare mag. I'm in Cali, so I have 10 round limits. My mags hold 8 rounds, my spare mags add another 16 rounds. My base carry load is 25 rounds.
While I could run out of ammo, I figure my attackers will run out of "fight" first. If I am wrong, at least I will go out in a Blaze.