I ran all seasons for a few winters here in CT when I had my 335i years ago. The A/S were OK and got me where I needed to go but I only had a 9 mile back road commute to work at the time. If you are worried about snow, A/S are not going to help you much. I ran them because I already had them and was too cheap to get another set of winters. If I were buying a new set I would get a dedicated winter tire set and not get A/S.
I should mention that when I ran the A/S I was not driving in snowstorms - I would either work from home on those days or drive my wife's car. A/S are not good when there is snow on the roads but they were ok like the next day once the roads were cleared. How much snow do you get avg? What are the temps like in winter? Do you have access to another car?