nokian mount and ground tires are the bees knees for winter city riding:
wide enough to deal with real snowfall, but the spaces in between the tread allow you to squish through slush down to the pavement, instead of floating over it. Enough studs to make riding on ice fun, but not so many that you feel like you're dragging a zamboni behind you all the time. The thick blocks of tread don't flex and skitter on dry pavement like knobbly MTB tires.
In addition to all this, they last essentially forever.