Best gun for home defense?

Can someone recommend a good gun that I would mainly use for personal home defense? My parents have always kept a shotgun, but I would like to avoid that if possible since its big and not as easy to hide out of the way from other people. However I live in an apartment and I'm worried about owning a handgun, because if I ever have to use it, I'm afraid of it going through the wall and hurting an innocent neighbor.