Not including my top show ever despite being too old for it, Franklin ( that preschool show ablutnthe turtle ), I'm going with Summer Camp Island as maybe 2nd place right now since I started rewatching it again. 6 seasons of a show starting off fairly episodic before coming together to tell what I consider a beautiful ending, even if it kinda feels like they had a network rush placed on them. Absolutely LOVE the final episode.
Though I have also been rewatching Code Lyoko since they have a full dedicated channel to the English dub of the show on yt. One of my all time favorite kids sci-fi TV shows period. Giant foreheaded minors attending a boarding school and fighting a virus capable of doing impossible tasks like making teddy bears turn into giant monsters or take control of rats to cause a plague or something along those lines? What's not to love?