Spoiler: it's Bill Murray.
Unrelatedly, here's an AV Club thing
about ten-minute-plus pop songs. I like long songs. My list has more psychedelic soul ('Smiling Faces Sometimes,' 'Papa Was A Rolling Stone,' 'Ball of Confusion,' etc.) and Afrobeat, though, and less 'Rapper's Delight.' If you want a crazy-long rap song, consider the Beastie Boys' 'B-Boy Boullabaise,' which appears on their list, or K-Rob and Rammellzee's 'Beat Bop,' which does not. There are some lists in here