In my experience, front drive is about the worst thing in snow IF
you know how to really drive. If you don't have any experience, it's great- just point the car where you want to go, and it goes. If anything does go wrong, it'll just understeer and you'll go wide.
The problem with front wheel drive in low traction conditions is it's very nature- your drive wheels also are your directional wheels. If you lose traction on them, you've lost most of your control.
RWD, on the other hand, gives the driver more control, though there are more things that can go wrong. When you lose traction on your drive wheels, you'll still have traction with the directional wheels, and vice versa. Example- if you're entering a corner in RWD, and the car starts to push, a quick shot of gas will usually break the rear end loose, and if you've got the skills to catch it after it starts to swing around, successfully make the corner. If you were in FWD, there's really nothing you can do but turn sharper and hope you get some traction.
RWD cars have better overall weight distribution as well; approaching 50/50 in some well designed sports cars; that makes for better OVERALL handling in all conditions (though, admittadly, very few drivers will have the need, or the skill to really exploit the edges of the performance envelope)
As others have said, ballast over the rear axle and proper snow tires will help imeasurably in low traction conditions as well. Remember too oversteer or "fishtailing" as it is often called, is not ALWAYS a bad thing; it's just differant; you're just not pointed in the direction your are going anymore. If you can control it, it's another tool. Understeer, on the other hand, is always a bad thing, though more predictable, and less unsettling for most people.