Im running a square setup of Goodyear Ultra Grip Ice WRT 255/55 R18s and they have been fantastic in the snow and ice here in Winnipeg. Only had one "moment" when I tried to defy to laws of physics
but came out ok. I believe the Goodyears are the most highly rated tires (for studless winter tires) on Tire Rack, for what it's worth.
Good luck with your search!