anon, there's like no debate about this, 99% of people agree
>first generation
seasons 1 and 2, possibly the best teen drama show ever made
>second generation
seasons 3 and 4, not as good as the first generation but still pretty good
>third generation
seasons 5 and 6, actually fucking dogshit, insane drop in quality, miserable to watch
>season 7/ the special episodes
idk if most people have even seen these ones but I remember liking them, they're really somber and sad