I voted shotgun, most likely my 870. With a pump 12 rounds would be readily available almost everywhere as would the possibility of finding parts for an 870. By varying my shells I could defend myself or hunt for food. With only one option versatility is the key. With all this said my gear I have has it set up for a pack with a shotty in a scabbard, an M14 on a sling and my .45 on my leg. All bases covered and easily carried.