Unfortunately, in many states the laws are not geared toward law-abiding citizens defending themselves or their property. If you are going to carry something, I would go with a short-barreled shotgun for these reasons:
1. Just the sound of pumping a shotgun's action has been proven effective in scaring marauders off in many cases.
2. It is a short range weapon, unlikely to harm someone at long range which could get you in trouble.
3. If someone is directly threatening your life at close range, a 12 gauge with buckshot should put a stop to them quick.
4. If you do go to court, using a shotgun sounds better for the defense than arming yourself with a "rapid fire death assault rifle" which the prosecutor may argue