I have 4 Glocks, 17,19,23 and 27. I am a senior citzen, 5ft 9 and 165 lbs. I like the 19 the best but seldom carry it. Why? I seldom carry the 17, 19 or 23 because their magazines are so long. I generally wear jeans and I cannot find a comfortable way to carry the magazines. On my belt they always dig into my side. In my front pocket, they dig into my leg when I am sitting. I can over come the problem by using a shoulder holster, but winter is the only time I dress right for that.
The Glock 27 doesn't hold as much ammo, but I can carry extra magazines on my belt or in my front pocket without discomfort. And, the 27 is a 40 cal which makes up a little for carrying fewer rounds. The model 17 makes a fine range gun but it is just too big for me to conceal with comfort. I carry to be as safe as possible while leading a normal life and I am not preparing for war. In court, I would probably have a hard time justifying emptying the mag on the 27 into someone. For those rare times that I might be trapped in the middle of no where and police are far off, the 12 gauge under the back seat will do nicely.