For small game your talkin .22LR or Shotty. Don't get me wrong, I see many advantages to the .22 mag and the two 17's. But if you're gonna use them you had better be dang sure you brain em. Any shots to the body can lead to less than desirable results for table fare. Plus, we are talking small game. You don't need a howitzer to kill em.
The 10/22 is great for small game. Reliable as the sun and accurate enough. I just went 4 for 4 on some starlings.
For shotty's I'll second the 12 and the 20. Ammo is too expensive and rare for the .410. It's not that you can't get ammo for it, it's that your choices are EXTREMLY limited. That and .410's just plain suck.
The big advantage the .22LR has over all the others, especially the shotguns, is that it is the quietest.