So for me it would have to be the original Dragon Ball tv show. I fell in love with the show around the Tien Saga for how meticulously animated the fighting was. Every punch and kick was seen and the focus was on martial arts. This continued through the King Piccolo saga, which I also loved.
However, I was massively disappointed with the Piccolo Jr saga. To me, it seems like the show switched from being focused on martial arts to generic energy blasts and poorly animated “flurry of blows” that really watered down the quality of the fights. Where before we had well drawn punches and kicks now we had people yelling loudly while blasting energy beams.
I’ll die on the hill that this was a “jumping the shark” for the Dragon Ball franchise that it never fully recovered from. Future DBZ seasons were a bit more creative (thinking of Goku holding Raditz while Piccolo blasted him) but the show as whole never really returned to being about “martial arts” the way it was before.
I feel like an old man shaking my fist at a cloud though, as I’ve yet to meet one single person who misses that focus/aspect of the old show.