I'm torn on which of my bikes to use for winter commuting. I ride about marathon's distance each day.
The first option is the purpose-built commuter. This would be the natural candidate because it is pretty much zero maintenance with internal gears and a belt drive, plus the roller brakes work equally well wet or dry.
But the roller brakes just don't work that well in general, and when it's dry a set of v-brakes easily outperform them. Plus, it's a really heavy bike and adds about 5 minutes to the commute. And you can't take it on the train during rush hour if the weather really sucks. The range on the Nexus hub leaves something to be desired for the hills. Lastly, it's a PITA to remove the rear wheel to replace a tube or swap on a studded tire.
The other alternative is my folding bike, which is considerably lighter and whose rim brakes are very effective on the smaller wheels. Of course it is welcome on the train. And it has twice as many gears (16 vs 8), so hills are easier. Of course there are cogs and rims and a chain to keep clean, so that's a pain. but I'm seriously thinking of getting a pair of studded tires for it and going that direction.