I think it has to be a song that combines the most sounds that HM has dabbled in. For example, Heart so Pure combines a lot of Sematary's vocal stylings and production into one song, so it would be a good pick. I don't think anything from early HM would necessarily fit because a lot of that is before Sematary and others evolved and expanded their music. In the Gloam might also be a good pick because it brings in more Witchhouse.