I'd pick the GEO just because its the best on gas and is about the most complete opposite of the Crossfire. I'd install some good snow tires on that bad boy and have at it.

My personal beater car is a 93' Regal Custom that has 116K on the clock. My wife and I got the car from her dad who's better half drove it into the ground. We've put about $3400 into the car over the past 2+ years, but it runs and drives great. You can't beat the 3800 V6, so I'd say anything with one of those motors is a good bet as well.