Currently I am mostly using this bike:
But have also commuted on:
I experimented with commuting on the fat bike last winter (my first for commuting) and wasn't happy with the way it handled, so this winter the Huffy and RockHopper are getting studded tires (two different types) to see how they handle the variable snow conditions I get here.
You can ride any kind of bike you want to for commuting - which ever one you like to ride the best is the one you should use. I currently prefer the Bianchi as it comfortable, absorbs road noise nicely and I can go (relatively) fast.
-Dave