Q: What do you recommend for home defense?
A: Whatever you're the most comfortable using. Chances are you're like me and don't practice nearly as much as you should. You probably don't shoot any matches and may have little to no training. If you've hunted birds your entire adult life, a shotgun is going to feel pretty comfortable. You will be familiar with the controls and function. If your only shotgun is a 32" barrel full-choked goose gun, it may be time for a downgrade, so to speak. Look for something with a shorter barrel that's easier to store, get into action and move around the confines of your home with. Don't load it with anything less that what you would hunt 250lb game with. Birdshot is for birds. Turkey loads are for turkeys. You need a projectile with more mass that is going to be able to penetrate deep enough to hit vital organs. 1Buck is a great load but hard to find so I keep 00Buck in my house gun. Know how your gun patterns and aim center of mass.
These same things apply to nearly all other kinds of firearms/shooters. Cowboy action shooters are to be feared. A lever action rifle is an excellent defensive weapon. It's very reliable, accurate and effective. Your average 30-30caliber carbine can be had for around $300 and makes a great budget do-it-all gun. It isn't a 400 yard coyote rifle and it's not a particularly good choice for squirrel or small game. For the bigger predators, however, it makes a great choice. It will put food on the table, and would be intruders in their place. It's cheap enough to practice with and fun to shoot.
Served in the US Armed Forces? Stick to what you trained with. Look for some variety of Ar-15 style rifle. It doesn't have to be fancy. It doesn't even have to be that expensive. It just has to work. The controls are right where you left them, magazines and ammunition are inexpensive and readily available. 5.56mm is a plenty fine round that has shown itself to be more than adequate for defensive reasons. Thank you for your service.
You may have noticed by now that I haven't suggested any pistols. There's a reason for that. A pistol isn't an easy gun to shoot accurately. This gets compounded quite a bit by stress and sweaty palms. In a bathroom, a pistol works ok. You're going to be very close, a pistol is easy to shoot at something very close. Coming out of your bedroom into your 50' wide main living room with hallways and doors all over the place unaware of the actual position of an intruder, a rifle is going to be much more effective.
I often hear "I just want something small in light to keep in the house. We don't need anything big." If self defense were that simple, we would give our infantry little .22 pocket pistols and a box of ammo to keep in a different room. Shoot what you're comfortable with. If there isn't anything you're comfortable with, find training. Rifles are easy to shoot, easy to learn to shoot and will serve you well in the home.
For me, home defense looks like this:
Stay safe.
