I've heard all of them and this one is the best.  Come on, think about all the memorable songs: Award Tour, Sucka Nigga, Electric Relaxation, Oh My God, and Lyrics to Go alone are enough to make this album a classic.  But Steve Biko, 8 Million Stories, Midnight, Keep It Rollin, and the Chase make this album a constant barrage of solid work.  It's just a good album; there is enough variety in tempos and themes to hold the attention, and each song is self contained enough to hold its own as a piece of art.  This album is honestly one of the best representatives of hip hop of the 90s (the best decade of rap), and one of the most finely balanced albums I've ever heard of this genre.  I can't say much else about this, it's like everything they tried to do suceeded beyond expectations; it is more mature and focused than the 2 albums that came before it and it is more fully realized in concept than anything that came after it.