I ride 35mm CX tires, and have found that they are good all-around for my location (Madison WI). Fluffy snow and watery slush especially are better with narrower tires (they cut through to the road). Car-packed snow is better with wide tires (you keep "breaking through the hardpack, but not consistently with narrower tires). Ultimately, each tire is a compromise for the range of conditions you encounter; which one is the best compromise for you depends on your riding conditions.