RWD with proper winter tires will be more than sufficient. And if you can, get a narrower width tire since that will help with grip. Just don't think you can drive the same way you could on dry roads, which is a common mistake many people make. I mean, c'mon, it's still snow on the roads!!!
If you use basic common sense you'll be just fine.
Oh, and don't forget about FWD cars. They actually perform better in the snow than RWD cars. It's a lot easier to PULL something on snow than it is to PUSH.
So the list should actually be:
AWD + Snow tires
FWD + Snow tires
AWD + All season = RWD + snows
FWD + All season
RWD + all seasons