I'm thinking WS50 since they're proven and cheap.

 

You need to decide what you want/need snow tires for.

Where I live I can winter isn't so bad mostly just cold. Plus I have another car for when it really snows. So basically I want/need a tire that will work well on cold/dry roads, plus if I get stuck at work and it's dusting of snow out.

For me, dry grip/performance is more important than snow/ice traction.

I'm getting "performance snow tires" I have them for my Passat and my Sienna. I don't have the M3s on either car, but as they come sized for sports cars and have great reviews at tirerack, that's what I'm getting.

Some snow tires are rated as "studless snow tires" or something like that, and are far better on ice, but probably give back in the dry handling department.