Winter driving ability?

We have an Escape AWD hybrid and are very happy with it -- not a single problem in three years, and it gets far better mileage than the Explorer it replaced (no kidding!).
We live in Colorado and have quite a bit of sudden heavy snowfall. The standard tires have worked fine. A hybrid, even an AWD model, will not have the same off-road or snow capabilities as a 4WD vehicle. If you live in an isolated area or work in an emergency-essential career (like a paramedic) and really need an occasional 4WD snow vehicle, consider a used 4WD (you should be able to find plenty of them at lower costs now) and only drive it on the days when you have to, rather than foregoing a hybrid. Your workplace may even have links to organizations that will come and get you if you work at, say, an emergency room.
I would check with the manufacturer (not the dealer or somebody's anecdotal advice) about whether you can fit studded tires, chains, or winter tires to them. The drive train on a hybrid is a bit different than most cars, and since drivetrain repairs are expensive (but rare), it's worth doing what they recommend.
The tires on a hybrid are "energy saving," which partly means they have less friction, which means they have slightly less traction and stopping ability. We compensate for this by driving more slowly, especially in snow and rain.