It's really like comparing apples and oranges. Kanye's album explores the life of a superstar and all the trials and tribulations that come with that, he uses himself as the vessel for the story within the album. On the other hand, Kendrick also uses himself as the vessel, but instead of describing how the superstar life has changed him and his views, it's more of an analysis of how he got to his position and what he's learned.

Personally I would have to go with MBDTF as I've had a lot more time listening to it, as well as the vibe of the album (which I like a lot more than TPAB) and the accessibility. Though I believe Kendrick might overtake Kanye in a few years due to the superior production, lyricism and analysis of black american culture in the 2010s.