The only thing Kendrick has over Nas is that people NEVER tried to pigeonhole Kendrick like they did Nas. People tried to crucify Nas when he didn't release Illmatic part 2 and went a bigger more expansive route with his music. Nas pretty much had to tell the world to kiss his ass while Kendrick has been given the grace to do what he wants and be appreciated for it.
Both have 2 legit classics and one arguable classic and both have a strong compilation album to their name.
What sets Nas apart is he's been 25 years in the game going STRONG. His lyricism hasn't fell off one bit across TEN albums, two group projects, and countless features. Honestly it's disrespectful to compare Nas or his career to anyone not named Jay-Z, Common, Ghostface, LL (people sweep his longetivity under the rug) or Black Thought.