I carry a Kahr CM9 on a daily basis with an IWB holster. My wife carries a Walther PPK/S .22 in an IWB holster.
We have shotguns, AR's and pistols in the house. A weapon is a personal choice, and no one can tell you what is right for you. A lot of people like to talk up Glock, but I prefer other manufacturers for no particular reason. Go to a gun shop and hold/aim a few of them and see what feels good in your hand. They all shoot bullets, but they don't all feel the same.
As far as stopping power, you have to realize that a hit with a smaller caliber that you can shoot reliably is a lot better than a miss with a large caliber. Also, as mentioned above, plenty of people use .22 as a defensive round. This is why I have no problem with my wife carrying a .22. She is a crack shot with it, and is literally uncomfortable with my 9mm that I carry. So, if she needs to, she can hit the target several times with a .22 instead of missing with my 9mm.
The act of being shot is very traumatic to someone, even in a high stress environment. So, taking stopping power into a defensive round is a small consideration in my opinion. Unless you are trying to stop a truck, shoot through body armor or some other highly unpractical situation. If you are looking to protect yourself or your family, get something that is comfortable to you and then look at the configurations and options.