Like mentioned, I think one of the major things to look for is a good fit. How does the sight picture naturally line up, how does your hand fit the grip without shifting around. Like a good pair of gloves, you have to try them on for size.

Speaking of gloves I wear XXL, but still prefer a single stack auto. I don't now why, but I just shoot better with the narrower grip.

The next thing I look for is safety. When I'm carrying, I may be breaking brush, chopping wood or whatever. Getting it out and into action as quickly as possible is secondary to not shooting myself or others accidentally.

And I always figure in the "KISS" principle, "Keep It Simple Stupid". When/if you do need it, it is likely to be when you are hyped up on Adrenalin. Anything that can go wrong will go wrong.

Like CalHunter mentioned, muscle memory is your friend.

My P-7 M8 is my go to pistol. As safe as you are going to find, feeds any and all ammo I've ever tried. Built like a brick. I read somewhere that they were due for a rebuild after around 15,000 rounds. I've got more than double that through mine and it still works fine. Only down side is they are a bit heavy and you have to clean the gas cylinder every hundred rounds or so. They stopped making them in 2008, my guess is they will eventually bring them back. Used ones can go for 300% of the original purchase price.

My guess is there is a reason even used P-7's are expensive, just because they are that good.