Glock 27, without a doubt in my mind.
Glock: Though the others might be reliable, the Glock shines above the rest when it comes to a history of reliability AND awesome DURABILITY, for sure.
Glock: a MULTITUDE of aftermarket parts, and easy to find replacement parts.
Glock: Simple to operate with few parts (especially outwardly), and thus less likely to fail, when you compare it to the others with all the bells and whistles. Simplicity trumps all when it comes to a weapon that you're going to use in a HIGHLY stressful life and death situation.
Glock: Simple and quick to take down and clean.
Glock: You can get a pinky extension if you're not comfortable with the stock grip.
Glock: You can easily heat up the back of the grip and push in that "hump" if the angle is too much for you. That "hump" is there because of the hole in the bottom-rear of the grip, so one can more easily grasp the magazine in case it ever gets jammed up there for whatever reason. Glocks were made for chaotic combat, and this is just another plus.
Glock: You can get 29 round magazines for the .40 models.