Part of the reason Nas is the GOAT is because he generally stays true to himself as an artist. Has he "sold out"? Sure. I remember when he was wearing shiny red suits with Puffy and that horrid Nastradamus title track. But in the age of the rockstar rapper, he's kept it realer than most.
After he crushed Jay-Z in their battle while going platinum on Stillmatic he was on top of the rap world. He could of just made shallow braggodocious gangsta pop songs and chick songs over Neptunes beats and rode that wave. But he basically walked away from that and turned around and made a dark, personal album God's Son. And ever since then he's just been doing what the fukk he wants. I remember seeing an interview where he said he made Made You Look the lead single purposely as a point to shake offany lingering pop commercial pop image he had.
Here he is at the apex of Stillmatic after beating Jay-Z rejecting a Coors Light commercial.
Diary Of Nas Streets Keep Callin - YouTube
A lot of people will knock him for not selling as much as he used to or not being a "boss," but he makes music for his core fans and wherever his artistic drive takes him, and that's why we love him.