You can tell how he's grown as an artist from Longterm, to Longterm 2 (which were both ehh to begin with), to Longterm Mentality (which, while better than Longterm 1 & 2, was still not that great), to Control System, which stands above the rest as his best work.
With introspective songs (Nothing's Something, The Book of Soul), hard hitting bangers (Track Two, SOPA), and overall dope songs all cohesively coming together to explain the premise of the album title, there's no doubt that Control System is his best work (so far).
lets hope Unit 6 be as stellar.