I have been alternating between my mtb (older hardtail with michelin country rock tires) and my road bike. Mainly because I haven't found a seat I'm comfortable with on the mtb yet. I love the relaxed ride of the mtb, but I've been getting off on the speed of the road bike lately. I use a backpack with either. My commute is 16 miles round trip, and I work 12 hour swing shifts, so the ride home is ALWAYS longer than the ride in!