Not a playlist, but I've always hit up Song Key Finder[1] when trying to figure out what songs might fit together for mashup-type purposes. They rank the songs

Not a playlist, but I've always hit up Song Key Finder[1] when trying to figure out what songs might fit together for mashup-type purposes. They rank the songs by popularity within their user community. [1]: https://www.songkeyfinder.com/ https://www.songkeyfinder.com/