The most "magical" attraction, I mean, there's a few different things I nominate for different reasons.
One Man's Dream: it brings everyone back to the journey and struggles it was to create such an empire, it brings into light a man that so many people don't even think about when traveling to Disney. It brings Walt back into the picture, everything he created, everything he went through to make Disney what it is today.
Fantasmic: The show brings together classic Disney characters, songs, movies, and most of all the adventures through Mickey's imagination! Which truly is the story of Walt's imagination, all of the people and stories he created (or altered into a more magial adventure) throughout the years. We watch Mickey conquer his fears and the dark side of nightmares, and come out on top, then the music swells an he pops up on top of that mountain and I'm a bawling mess
Runner ups:
Phillharmagic: It houses such classic Disney tales/songs and the 4d makes the kids go insane, they reach out to help save donald, do try and grab some of the jewels, it's just fantastic.
Festival of the Lion King: Again, classic disney movie and characters and music, and the way the theater works and the way the entire show just immerses you, you're really part of the magic and it houses some of the greatest talent on property! It's amazing and brings me to tears every time