I'm a Police officer and Tactical Instructor. I carry a Kimber .45 on duty, and have several off duty guns. There are 2 different outlooks. Large caliber / fewer rounds, compared to Smaller caliber / lots of rounds. My dept's out look is to carry a large caliber / fewer rounds. I respect that outlook, but given my choice i'd go with with a smaller caliber / more rounds.
I have taught traffic stops, building searches and ambush scenario's with simunitation's, and I can tell you that I go through that 8+1 rounds from our Kimber's very fast. When I am teaching other dept's that carry high capacity 9mm and .40, you really see the advantage to having 16+ rounds.
Another thing to take into consideration is to carry a handgun that you can handle. I'm not a small guy. 5'11", 225lbs. I workout and shoot all the time. I can can handle our .45's no problem, but naturally I can fire my 9mm and get back on target much faster then with my .45, which equals more rounds on target faster.
My main off duty carry guns are a S&M Airweight. Plus's are: it's hammerless, light weight and I normally just slip it into my pocket. Minuses: It sucks to shoot, because its so small and light weight, and it only has 5 rounds. The other gun I carry most of the time is one my Glock's. The 17 Gen4 lately. Plus's: Fun to shoot, 17 rounds, proven reliability. The only minus is the size for concealing it.
I'm a big Glock fan, but some of the guys mentioned the Springfield XD and XDM. I have shot them and really like them. A very good choice. Your best thing to do is decide on the caliber and size (compact or full sized) and go to the gun store and hold the weapon to see what fits you the best. Stick with Glock, Springfield, H&K, Glock, Beretta, Smith and Wesson M&P, Sig... Yes, I said Glock twice
Paul B
A magazine holds bullets, a clip goes in you hair.