[jboot]

If you can only have one gun, get a 12-guage pump shotgun with a smooth bore (i.e. not a slug gun). It is easily the most versatile firearm that anyone can own. The Mossberg 500 is cheap and robust. The Maverick 88 is cheaper and is just as robust. The Remington 870 is tried and true. There are other brands. Almost all of them are suitable for home defense. Select a self defence load, though. Don't use bird shot (#6 - #9).

If you must have a pistol, go with a standard size revolver (not a snub or "airweight" with a 4" barrel in .357 Magnum. The kick isn't bad in a standard frame gun and it hits much harder than .38 Special. Taurus and Ruger make inexpensive revolvers. Smith & Wesson makes expensive ones. They all work well. Fixed sights are preferable for home defence.

[AFPhys]

“Select a self defence load, though. Don’t use bird shot (#6 - #9).”

What do you consider a “self defence load”?