ESC isn't magic, but its been proven to stop a little fishtail from turning into full blown off road excursions. In terms of snow driving I'd rather have it than ABS simply because in loose surface conditions like snow no ABS is often better than ABS.
An impreza would be great, but in snowy regions they tend to be way overpriced. I'd be thinking more about sedans that came in it but aren't what people usually think. VW 4motion cars. I know golf had it on some models. Maybe others. Ford fusion came in AWD. Maybe the old ones are cheap enough now?
Oh I agree. Of the three: stability control, anti-lock brakes, and traction control (they usually all come together now), stability control is by far the most useful. I do most of my winter driving on city streets at low speeds though, and seldom if ever does stability control kick in. At higher speeds such as slippery freeway driving, it would be much more useful. For instance, about ten years ago my wife hit the brakes in the middle of a turn at about 50 mph on the freeway in a snowstorm, and we fishtailed across the median into oncoming traffic. Fortunately no one hit us, and no one was injured, but antilock brakes and stability control most likely would have prevented that. My point though, was that none of those electronic aids will really prevent getting stuck. For that you need good tires, lots of ground clearance, and fwd or even better, awd.