First off - Love the changes.
- A tag for %AlbumArtist
- A tag for %Date
- A tag for %Copyright (immediately below track listings on each album's page. This would help ID the version of a album - 2002 remaster vs 2012 remaster - for eg)
- The ability to specify the size of the album art (note that if you use a URL to pull an album's art, you can specify the desired size and quality (see the file name at the end of this sample url): https://e-cdns-images.dzcdn.net/images/cover/23820239aed4256895655c76674ca075/500x500-000000-80-0-0.jpg)
- The ability to tag a track with multiple album art images at various sizes (1200x1200, 500x500, ...)
- The ability to tag a track with artist's art (user defined/multiple sizes here would be nice too)
The %AlbumArtist tag is the big one for me followed by the ability to add sized album art (the player in my car chokes on larger album art). The others would be icing on the cake.