Lots of good arguments on that other thread (I'm behind on reading it), and as tempted as I am to say I'd cling to a 12ga or a 22LR bolt gun, as of this writing it's my Gen4 Glock 22 (.40S&W).
It shoots a pretty much do it all (don't start, guys) pistol cartridge, I shoot it very well (15 rounds into 2" at 10yrds or 8" at 30yrds on a good day), it can take up to a 22-round mag, it's dead reliable with a variety of ammo types, I have a lot of ammo and can make a lot more, I can carry it concealed if I have to, it can take a drop in 9mm conversion barrel and mags without further modification (though I've read the extractor can be an issue), and I can practice with it at four different ranges without making a long drive. I realize the .40 is not considered a hunting round but I'm quite sure I could make back-yard-range head shots on a few of my 30 kajillion squirrels (until they figure out why their buddies aren't returning from nut gathering runs) if the law were a long way off and I was truly hungry.
If they come to take away every gun from all of us save one, that's the one I'm keeping. If I could keep just two, I'd add the .22rifle. Three, a 12ga pump. But they're not coming for our guns, so I'm keeping the rest as well.
