9mm firearms are going to have a higher capacity due to round size, and are cheaper to shoot due to ammunition costs. When the ammunition shortage was the worst, only 40S&W seem to be more commonly available. I like 9mm and 45acp, found that my arthritic hands didn't care for the recoil "snap" of the 40S&W, but I am an admitted "wussy" so you can take that with a grain of salt. The highest recommendation when it comes to home-defense and CCW, is to pick the firearm that is the most reliable, and you are most compitent with.