TPAB conveys the same sense of racial despair and overall feeling of racial isolation albums like The College Dropout and Late Registration admirably communicated.
MBDTF is Kanye's shitty ass justification for his over the top ego as he becomes whinner and bitchier. I couldn't give two shits about him sampling King Crimson.
That being said, Kendrick saying that "To Pimp a Butterfly is going to be taught in college courses; [I] truly believe that" makes me believe he's heading in the same direction as Kanye.
tl;dr
TPAB > MBDTF but only because he ain't a bitch yet.