The show peaked during the Jonathan Turner years

Definitely. Joey, Frankie, Harley and Eli also gave the show a big boost.

Absolutely. The writing was spot-on, both the drama and comedy. Eric found a sweet spot in between cool and stupid. Topanga wasn’t too strange but she wasn’t too straight and narrow either; she was similar to a real-life teenager. Shawn had personal problems, but it hadn’t turned into this brooding personality. And Cory was a real boy: figuring out how to talk to girls and how to have a serious relationship, while not holding these impossible ideals.

And Vader Time.

Seasons 2, 3 and 4 are the best.

For me personally, the later high school/early college years (but before Eric got fat & turned into a complete mental case) was the period I was most invested in the show, where they expanded the cast of young regulars with Angela, Jack & Rachel, who I think assimilated into the main cast very naturally in a way that didn't feel forced. I didn't hate the Turner years but I was never crazy about Turner's "hip teacher" schtick & his overemphasized relationship with Shawn. I also found the recurring bully characters to be very lame caricatures.

Yeah agreed. 1-5 was awesome. 6 the quality started to dip. 7 was atrocious