If push came to shove and I had to get rid of the other eleven, the one I would keep would be a 12ga 870. I prefer other guns for everything but waterfowl, but I've done it all with an 870 also.
You can get 12ga ammo to do ANYTHING (anyone need a flamethrower?) Change the stock and barrel and teach your kid to shoot with superlight target loads. Need to kill a turkey? a goose? shoot trap? squirrels? some a-hole that kicked in your back door? It'll do it all. I've seen guys have to borrow a goose guide's pump when their autos froze up. It's sometimes nice to have an extra shot when the only ducks of the day pile into the decoys or another rooster flushed just as you whiffed the first one - twice! It's the one I took on a caribou hunt to shoot ducks and ptarmigan when I thought it might fall out of the scabbard strapped to the wing of a SuperCub.
It would be boring but If I had to whittle it down to only one....
