While I was adding MusicBrainz metadata to the playlist format survey yesterday I realized that it was the only playlist format to follow best practices. It invents a minimum of new names (though there's a bit of overlap with the RSS 1.0 audio namespace). It uses very precise definitions of data elements. It doesn't abuse external namespaces. The documentation is clear and unambiguous.
Given what a disaster music metadata formats as a whole are, this is a pretty big accomplishment.