It seems like there are definitely two philosophies on this. One, and this seems to be the traditional one, is that you carry a cheap, beater type rifle or shotgun. The other is that you carry the best you can for defense. People subscribing to the former seem to be more concerned with four legged targets of opportunity, while the latter seem to be more concerned with repelling boarders. The concern with theft is significant, but I carry weapons I would want in my hand if I need them: a Glock 20 that also accompanies me on hikes, and a Ruger GSR that provides a longer range option. While that's not cheap, I can't quite bring myself to leave my AR in the truck all the time. If I had one, I'd probably think pretty hard about a .300 AAC pistol with brace and red dot. Between capability and legality (state lines and all that), that is a pretty good package.