I just got the Conti DWS tires. They are asymmetrical and have proved to be better than my stock michlin Sycromes. That said I feel like they make be a little softer and they don't seems to handle high speed bumps as well, but so far no issues with blow outs. I drive in NYC a lot and find myself hitting large potholes frequently.
I have been using Vredestein Wintrac for the last 5000 miles and have found them to be superb in the ice and snow and perform just as well as the Conti tyres that came on the vehicle. They are 255/50R20 size, about £135 each from Camskill in th UK