I would say it depends on where you live and what is readily available to you. What I mean is........Do you wish to leave your house and get right to riding like most roadies can? Or.......Do you prefer to get away from the hustle and bustle of life and retreat to the secludeness of quiet single track trails or city pathways?
That I believe sets the tone and ultimate decision.
I have done both and now I am back to mtn. biking again. I love road riding but the nuts on the road I call cagers are getting worse and worse at driving so I will once again take my chances with trees; hunters; bears; and what have you in the wilderness again.
Good luck.