Wander Over Yonder
Season 2 had a lot of fantastic episodes, as the show's creative team explored many different genres of fiction to pay homage to.
It's just a shame that Disney gave no hoot about the increasing popularity it would receive after introducing a fantastic female villain, along with wackier humour and homages that would go way over kids' heads.
While serialized formats are starting to overstay their welcome, I would have definitely appreciated learning more about Wander, Sylvia, Hater, Peepers, or even properly conclude Dominator's arc without her wandering free, ready to reoffend at any given time.