Having been a huge fan of Adventure Time since I was 12, this one is pretty nostalgic to me. I remember watching an episode of Adventure Time back then on our family television (I think it was "Trouble In Lumpy Space") that lured me and the whole family into the series. It's got everything a child could ever dream of: adventure, princesses, and all things mathematical!
Other than that, Adventure Time had always been so great at telling their stories, with character arcs that just make sense and are so raw that gives the antagonists of the story their own character development which makes you love them more. Each and every character are unique in their own little way.
Adventure Time: Fionna and Cake tells the story of the two titular characters who gets stuck in the multiverse that is told so perfectly and alters infinite realities massively. The creators are never afraid to test our their abilities to further expand the stories and how literally anything could happen. So far, "The Winter King" and "The Star" are my favorite episodes of the season -- and I am craving for more. I already love Gary and Marshall Lee's storyline, as well as Simon and Fionna's dynamic.