Used flat bar MTB for many years, but as I've got older I found myself doing less proper MTB stuff and sticking mostly to trails (NCN and similar).
Last summer I had a cycle commute forced upon me, which saw my miles and time in the saddle rise massively, resulting in a recent change to a drop bar cyclocross bike. This choice of bike was originally so that I could still cycle on trails etc. on days off, but be better suited to commuting on the roads.
In the past I always avoided roads whenever I could, however when commuting, the choice is more limited; and I have enjoyed the transition to a drop bar so much, that I am already looking to add a proper road bike to the fold.