I predicted that most of the list was going to be approved maps....
It was phrased wrongly IMO. This list described people's favorite maps in osu. Favorite maps != best maps in general. If we're trying to avoid popularity contest and song bias, it's hard to judge the best songs in osu from which songs we've enjoyed the most, because song choice does play a large role in the enjoyment one has in playing the map.
It would have been more accurate if there was different categories. We could them split overall favorite songs in one category and then have a different category for best technical maps (as in gameplay), and best customized. Also this was obviously biased towards a certain mode. It would be obvious that people from other modes would favor the approved maps, because they provide a greater challenge. If we're going for a more fair rating, there would be a category for best technical, and best all around mapset (mapset that overall was highest quality, restriction - must contain full ranked set to count).
P.S. no I didn't vote for gangnam style. I change my vote long ago.