Your best bet is to get in somewhere and handle a bunch and shoot as many as you can. For what it is worth most people that don't like Glock has to do with its more swept grip angle, and the dead in the hand feel, but they are the AK of the pistol world, and most people learn to shoot them very well. I own: 3 x 1911s, Sig P226 9mm, SW MP 9mm, H&K P2000 .40, Glock 23 .40. If I had to choose one it would be the G23 or the M&P 9mm, purely from the perspective of being the most efficient tool.
I wouldn't worry too much about caliber. 9mm, 40SW, 45 ACP are all adequate, and all will punch through a car door. I do think that the 40 is a decent middle ground between capacity and energy. A good quality defense round is important, in fact the FBI just switched back to the 9mm, and that is saying something when the only reason the 40SW was designed was for their use.
Interesting fact: the DOD has done studies on average accuracy in combat, and in those studies, across all services engaged in ground combat, 10% of rounds fired in a firefight hit their target. You may see a higher hit rate inside of 7yds, but once the blood and adrenaline are pumping, things get crazy and it is all muscle memory. That being said having 13 instead of 7 sounds pretty good to me.
Whatever you buy for a pistol, get a good holster for it, and then practice getting your pistol out of it and into action. You need to practice this with a sweatshirt over it too. The pistol is worthless unless you can get it pointed in the right direction promptly. If you have plenty of time to draw, you probably had time to run away, and in most states you have a legal obligation to do so.
Also, if you are going to be using it for home defense, make sure you put a light on it. It is always a good idea to identify what you are about to shoot at.
