Voted 'other'; the poll fails to include "flat bars w/bar ends", which to my mind are quite distinct from "flat" as a category.
I use a pretty standard flat bar (600mm/8 degree sweep) with bar-ends and Ergon grips. Have done for years.
Reason 1: I prefer shifting and covering the brakes from "the tops" while in traffic and
Reason 2: I find this set-up more than comfortable/aero enough for me on windy/long/century rides etc.
Reason 3: I don't engage in Cat 6 racing, and I'm too chicken s**t to descend at 70kms/hr, so don't care about 'the drops' for sprinting and descending.
Caveat: I have only one bike. If I do add a second, purposed only for longer distances out of the city, it would have drops/brifters. Just because.