On the road, long distances, possibly continuous headwinds I vote roadbike. Mine is a cyclocross frame with Midge Bar One drop bars. I think frame choice is more a consideration. I used to ride a mtb full suspension. I first got rid of the suspension fork, replaced it with my cyclocross fork. I was committed to a frame in the near future.

When I finally got it all and put it together, I was more than a little surprised at how much easier it was to cover my 22 mile roundtrip commute. I am riding as a singlespeed 48x11 that didn't exist on the mtb and faster now than ever. The tires and innertubes for my road/cyclocross bike are much lighter than the mtb counterparts.

Ergonomics of the current bike win handsdown for commuting over the road. I ride the entire trip in the drops or on the hoods. Headwinds don't affect me nearly as much as they did on the mtb.

The longer the distance, the more a roadbike becomes attractive.