I live in a fairly gun-friendly state. Open carry is not only legal, but protected in MT. Additionally, one doesn't need a permit to carry concealed outside of city limits, the state is "shall issue," and there are to my knowledge, no laws concerning printing. Finally, there are no state laws limiting magazine capacity or other nonsense.
I am six and a half feet tall. I wear a size 15 shoe and my hands are proportionately the same size as my feet. I don't like sub-compacts or any handgun that doesn't allow me to get a full grip. I refuse to deal with the "tea cup grip," trying to maintain any standard of accuracy with my pinky hanging off in space. And when barrels get too short, it not only cuts down on sight radius, but also starts to feel dangerous. I caught myself just starting to apply trigger pressure to a 2 inch barreled .357 Magnum once with a digit hanging out in front of the muzzle. That's a mistake you only make once. I don't trust that under duress, grappling with an attacker or dodging bullets, that such a weapon would be as much a danger to myself as it would to my adversary.
With all this in mind, I gravitate to high capacity polymer framed autos that have a good firepower to weight ratio. I carry a Gen III Glock 20 10mm Auto. My list would look something like this:
1. Reliability (of course)
2. Shootability. A little subjective, but includes everything from size and ergonomics to sights and recoil impulse. Basically has to be big enough to shoot well.
3. Firepower. Again, subjective, but generally understood. Handguns are unreliable stoppers with a demonstrated history of inconsistent performance, and they are used under desperate circumstances. I want my handgun to have the capacity and the relative power to allow me to respond and end the confrontation or break contact and flee. Fifteen rounds of 10mm Auto is about as much firepower as one can discreetly carry and control under stress.
4. Weight. Arbitrary, I know, but it becomes a drag having an anchor attached at the hip. I use a good belt and holster, but realistically, we have to keep the weight of the handgun reasonable too. This is one reason I prefer polymer-- you can fit 15 rounds into a polymer framed handgun and still be under 2.5 pounds.
5. Ease of use/maintenance. Keep it simple. You're not going to want a complicated manual of arms when people are trying to kill you. Striker fired autos are very simple to employ, with minimal controls and a consistent, serviceable trigger. I generally favor popular models with readily available aftermarket support, and I like guns that are simple enough for me to take care of. A Glock is simple enough and popular enough to find holsters and accessories and for the user to fix or replace anything on it, so maintaining it in the long term is straightforward.
6. Trigger mechanism. I am avidly opposed to two distinctly different trigger pulls on one gun, and consider double action autos to be a solution in search of a problem. A crappy trigger is not a safe trigger. A long, heavy, gritty, crappy trigger only makes the pistol harder to employ effectively. I consider it the equivalent of removing power steering from your pickup and calling it safer. So I don't care what other features a pistol has, if it forces me to deal with a 12 pound trigger, I am not interested. I will look at DA/SA pistols only if they have an ambi safety that allows me to bypass the DA and carry it cocked and locked.
7. Size. Not a huge concern for me, but I am also not packing a Desert Eagle or AR pistol. There is an upper limit to the size it is practical to carry. Handguns are carried because they are discreet, so I need the handgun to be big enough to shoot, but also small enough to conceal on my wardrobe, which is typically cargo pants with an extra large t-shirt and a light jacket or hoodie.
8. Cost. I work for a living. I don't get to buy nearly the number of guns or ammo I would like because funds are tight. Realistically, I need to be able to afford the firearm and it's magazines and accessories. Another strong point for polymer is economy. You can get a lot of pistol for your money shopping polymer. Glocks provide reliable, lightweight, high-capacity portable firepower at a price that is attainable to most of us.
9. Brand loyalty. I will admit it, I just don't like certain brands, for whatever reason. Mostly it has to do with a violation of a previous rule-- Beretta for example forces one to carry in DA mode and then places an unintuitive safety in the least sensible position, so I am not a fan of them.
10. "Second kind of cool." This is a Nutnfancy term, if you follow him on Youtube. Difficult to explain in depth, it pretty much means that the pistol appeals to me in some way that I acknowledge makes little sense, but which I can't ignore. Again, this usually has something to do with a previous rule-- like the Glock 20 being second kind of cool because it has industry leading firepower to weight ratio, and knowing this makes me feel like the baddest "dude" in the valley.