Warp - I feel like we're getting a lecture here...
I picked a shotgun. I'm waiting on my carry permit now and plan on carrying, but if I could have only one, at least at this point in my life, I'd pick a shotgun.
As another poster mentioned, a pistol isn't the only tool in the shed as far as personal protection goes. And truth is, I've made it this far without carrying and have managed to keep myself out of trouble one way or another.
And if I had to carry, it's legal in my state to open carry hand gun or long gun. And if discretion were required, a "coach" gun, or even an Over-Under with say 26" barrels broken down could fit into a backpack, and carried without suspicion. A handgun would be quicker to employ no doubt, but still either shotgun could be carried anywhere, and be available at just a moments notice.
And pulling back a little closer to reality, the shotgun is better suited to hunting than a handgun. It's also loads of fun to go clay target shooting (a hobby of mine.) And it sure would handle any home defense situation with aplomb...
I can definitely understand others choosing a pistol. I think it would be a very wise decision. But if I only got to have one gun, and the choice were mine, I'd pick the shotgun.