I started of riding and racing mountain bikes and only had a mountain bike for ~4 years. When I got my first road bike I was living in a large urban area with crazy drivers and I *hated* road riding. I would only drag out the road bike for group rides. I used my mtb for commuting as well and would spend long days linking all of the local (within riding distance) mtb trails.

A few years ago I moved to a small (30K) town in the midwest. We have miles and miles and miles of narrow, twisty, lightly travelled country roads. I can ride 10 minutes out of town and do a 60-miler and see maybe 5 cars. It's nirvana!

Sadly, the trade-off is that mtb trails are at least a 20-30 minute car-ride away

Like I stated before; I guess I'm lazy. I prefer whichever is easiest