It is absolutely impossible for me to choose just one song. I love Zelda music too; my iPad is absolutely FILLED with it.
But here are some of my favorites:
Fi's Gratitude
http://www.youtube.com/watch?v=QEbFLSfHqQ8
Realm Overworld
http://www.youtube.com/watch?v=5W_bFLwB0WY...