When it comes to driving on ICE, 4WD doesn't help. Siping on tires, does a little bit.
I have installed Treadwright tires with Kedge Grip compound on my Jeep for the winter.
Kedge Grip is a rubber compound that contains crushed walnut shell and ground glass. The tread surface feels like sandpaper, and when the walnut and glass come out, they leave behind a gozillion edges to bite the snow. So far this year, I've had two chances to drive on ice and packed snow. Very impressed. They grip the ice and packed snow much better than my Mud-Terrains (which were well siped). Come spring, I'll jack up the Jeep and swap out these tires for a new set of Cooper SSTs on aftermarket wheels. I'll store the Treadwrights for the next winter....
My Cooper S/Ts were great in deep snow. So-so on packed snow, not good on ice...
The Treadwrights were surprisingly good in deep sand, and adequate in mud. They are excellent (relatively) on packed snow, and grab as well or better on ice than my studded Dick Cepek tires (on my old YJ).