My favorite theme, and stage from the phenomenal, and when all is said and done, my favorite 3DS game ever, Kid Icarus Uprising!
I remember playing this game, and, as with any Sakurai developed game, loving the music. I looked up who did the music and, well, everyone did. This all star cast of musicians including some of my all time favorites such as Yasunori Mitsuda and Motoi Sakuraba. Everything about this game is great.