What is the best weapon for self defense?

You should have the firearm you are comfortable with shooting. If a gun is not comfortable, you will not practice, and that might make you miss a threat and possibly hit a bystander. Worse, a gun that is too powerful for you to handle comfortably might lead to being afraid to fire it when necessary or it might make you develop a flinch.

At the same time, the gun should be a realistic defense arm. I would say that the minimum defensive handgun caliber acceptable is .380. .32 might work if you are a really good shot or have the need for an extremely small and light pistol. Smaller calibers can most certainly kill, but do not stop a person effectively, and stopping is the big thing in defense.

If you are a novice, or cannot/do not want to carry a pistol, a shotgun is a good choice for home defense. Pick the largest gauge you are comfortable with. Even a .410 will be quite effective at close range. A .410 slug is a sizable chunk of lead.

== == You should take a safety and a users course at your local sheriffs office or gun shop, as well as obtain the proper licenses. Shooting on a regular basis is loads of fun and relaxing as well.