I hold this show very dear to my heart. Before I discovered the show I was in a phase where I wasn't particularly... happy in my own skin. Every character I saw on screen that looked like me was always either a token, loud and obnoxious, a "comedian" who's best jokes are "I'm black and that's it" or the antagonist. It got to a point where I started thinking like "I look like these characters but I'm nothing like them. Am I better?"
Then I came across this show and it was the first time where I saw a black girl who wasn't a caricature but instead treated like normal girl in high school. This show also introduced me to the queen that is Zendaya herself. She's just brilliant in every way possible. I also like the fact that she had creative control on the show and forced Disney to do things differently, introducing much needed diversity and nuance to their shows. And by diversity I mean proper diversity.
With memorable characters, an awesome theme song and a great cast this show served as the perfect escape and comfort show for me. It helped me down a path to self-love and being comfortable in my skin so that's just another thing that makes it so great to me.
Also main characters are never my favourite characters in any movie, show or book. But in this show KC Cooper is my fav character, and not because she's played by Zendaya, but because as I said I see myself in KC. Very rarely do I relate to a character, but KC is one of the few I actually did relate to a lot.