I want it for protection.
I'm not a hunter so I don't think a rifle is what i am looking for.
maybe go to a range every once in a while.
Semi-auto pistol in 9mm.
Relatively cheap to shoot
Capacity over revolvers and shotguns a plus.
Prices, quality, and reliability vary greatly.
Revolver in .38 spl/.357 mag
Preferably .357 because you can shoot both .38 and .357.
Ultra reliable, easy to use especially for people who have trouble racking a slide.
Fairly affordable for a quality gun.
12 ga pump shotgun.
Jack of all trades. Paper, clays, birds, mammals, and really big mammals, inanimate objects

and everything in between
Cheap, reliable, easy to use.
All of these choices are relatively cheap to shoot and IMO offer enough punch for SD/HD if you use the right ammo. The handguns have a steeper learning curve and will take more practice than the shotgun to shoot accurately and precisely.