While I appreciate the effort, I disagree with the criteria. I understand the point you are making and appreciate that Em is still ranked at number one. Still, a list of the greatest rappers ever that includes Puffy but not Nas automatically disqualifies the criteria.
I do think sales should be in consideration, but music is far less about numbers than basketball because rap isn’t a sport. It’s a competition which means there are intangibles to consider when scoring. Good read, though.