Ehm there are no good Rick and Morty Fanfics. Avatar the last airbender is often dropped like that fanfic where mc became Zuko, but was discontinued. Star Wars could also use a good new fanfic.
Cirque de Freak and Danny Phantom there was a small fic about it on fanfiction.net but it didn’t progress far it’d be interesting to see someone do something with it. Plus both are great franchises.
treasure planet (A movie), Bobiverse (A book series), Borderlands (A game series) these are all fun and recommend watching reading and playing besides making a fanfic for.