I don't. BM is not a democratic game, and some things are not about opinions. You don't vote on the speed of light. Comments I appreciate, votes mean nothing.
Then scratch the quantitative data and get the players to comment. Not all do the forum thing. It could be some GM ran game-wide referendum with a link in the announcements that leads into a page with a simple box where to click a continent you want to keep and reasons for why. Though perhaps the forum is enough of a sample when it comes to the particular features of any given island.
I would keep Dwilight, because of the unique map, interesting sea travel, doughnuts around the cities, SMA and Sanguis Astroism, even if I will likely never play in that religion.