I'd probably have to go with the magesty of the Song of Time. so Epic.
But my other favorites are Epona's Song, Saria's Song, and Zelda's Lullaby in that order perhaps.
Epona's song is so sweet and relaxing. Saria's Song is upbeat and cheerful. And Zelda's Lullaby is simply beautiful
Also the Song of Stroms is catchy af
I was never really fond of it though it's just rather pleasant when all of a sudden it starts playing in my head