This blog is dedicated to practical handguns mostly chambered in 9mm. For defensive purposes, you need to choose a gun for home defensive and one for carry. This can be one or two guns as you can find a gun that meets both needs. The gun you choose needs to meet the needs of why you need it.
Some bad advice is your home defensive gun should be a 12 gauge shotgun because you can't miss. The problem with shotguns as your home defensive gun is your home has the potential to be a complex area with close drywall walls, multiple rooms, stairs, and corners. You need to be aware of who is home and where they are to know your backstop. Shotguns are difficult to control for the novice shooter in maneuverability, recoil recovery, and reload. A pistol is far more accessible and allows you to easily find cover or concealment, shoot on the move, and reload.
Having said all of that, I do have a 12 gauge pump action shotgun at home. It's not my primary home defense gun but it's there if I need it.
The home defensive gun should ideally be the largest caliber you can accurately fire on the largest frame for stability. Any full size service revolver or semi-auto pistol will be a good choice. The preferred caliber choices for revolvers are: .38 Special, .357 MAG, .44 MAG. The preferred caliber choices for semi-auto's are: 9x19mm,.357 SIG,.40 S&W, .45 ACP, &.45 GAP.