45 carbine (USC45) or bushy 16 or 20 inch ar. i have heard that carbines can be a good choice for civilian/ home protec. in today's homeland security minded climate, couldn't hurt to have a little more firepower at your disposal in addition to the glock or 4 inch revolver in the nightstand eh?  ( i know this is an ar-15 site so i can expect the answers to be a little skewed but, i have posted same question on HK site.) i'll share their responses too.

Is this a trick question?

I would say go with the AR just because you can get a pistol caliber upper for the rifle and you can have either one depending on your mood. That is the joy of the AR system, lots of ways to change it.

Buy them both !

In the house? Shotgun or pistol would be my choice.