Votes for Bahamut are probably either:

A) Voter doesn't understand/didn't bother to figure out how the poll works, and is voting for their favorite.

B) Backlash against the "Bahamut is the best" foregone conclusion based on damage done. This second one I'm almost tempted by myself, as I like to pretend that a summon can be cool for reasons other than doing a truckload of damage.