I don't think there is much objectivity in placing Section 80 or GKMC above TPAB. In most aspects you rate an album
The lyrics are more intricate and complex (without sounding rappety rap rap). The storytelling is better. He went into more concepts and themes. As a hit, Alright > Swimming Pools or Poetic Justice (yuck) or HiiPower. The production while more expansive is done at a high level. And find me a stretch of 3 songs on GKMC/Section 80 that match Momma > Hood Politics > How Much a Dollar Cost (personal metric of mine, don't take this too serious)
You can say that you sense Kendrick trying too hard on TPAB... duh that's the pitfall of trying to evolve, and any classic left-of-center Hip-Hop album will have those moments (Mamacita on Aquemini comes to mind) but I was just glad someone, in this sterile music scene, was willing to take an artistic leap and push themselves beyond their comfort zone (shoutout to Da Baby and Drake). Wish more artists actually did this.
That said, there are legitimate reasons for liking Section 80 or GKMC more. Those are more conventionally produced, the concepts/themes are tighter, the storytelling is more linear, and of course Poetic Justice (yuck) appeals more to the casual crowd. There is little in TPAB for the casual.
Side note: Section 80 doesn't get enough credit... if ever there was an album that captured the angst of the 80s generation in a bottle... another topic for another day
I personally have TPAB > Section 80 > GKMC. Case can be made for all of these being legitimate classics in their own right.