I voted for Medulla, However, I think that the poll should have been titled "What is your favorite Bjork album" rather than What is the best Bjork album.
BTW, the surround sound mix of Medulla is absolutely stunning. If you ever get a chance to hear the 5.1 mix from the SACD version of Medulla, played back on a good quality multi-channel surround system, i.e. not through a "Home Theater In A Box" system, I think that you will be impressed.
That said, I can well understand why many people are not that fond of Medulla since it is perhaps Bjork's least accessible recording and at times it can rather difficult to understand.