I love knowing if it snows, my AWD Subie will get me home. That's only if it doesn't get to deep. You still might be okay with a good set of winter tires on the Ford just not sure since I never drove a Focus in the winter.
As a side note: The 2012 Impreza is getting a lot better gas mileage then before! The Focus get's a little bit more because it's not AWD.
The Good: Plenty of leg room and trunk space for the Impreza Sdn.
The stereo sucks in all the Impreza's not mater what model or options.
For me I would stick with Subaru since I've been buying them new since
2003 and overall love the car and the resale of them.
In the end it's going to be a tough decision for you because both cars has their good points and bad points. I think the main issue is the AWD or FWD. What are your roads like in the winter and how comfortable are you driving in bad conditions? You should be much more relaxed with an AWD car in the snow/rain then with a FWD or RWD car.