@Hexagoon

Toplist is not the same thing from what I can tell. Was looking through the libspotify documentation and toplist gives you a list of the most listened tracks, albums or artists by zone or just for yourself. It is a pretty nifty feature to have if you want to listen to the most popular songs in say UK but won't give you the most listened songs by an artist from what I can tell.

However, if I am not wrong, you are implementing the "popularity" XML tag as the field you call rating, right? That tag seems to tell how many times has that song been played, in relation to other songs which are sent in response to the search query. So if that is indeed how you work out the rating header, then sorting by rating should give us sorting by most played (This is what I used as reference)