I have too many to name just one.
The original Legend of Zelda intro theme, the Overworld theme, TLoZ Dungeon theme.
All the music in AoL.
The Fairy Fountain theme.
The original Kakariko Village theme.
Castor Wilds, Elemental Shrine and Temple of Droplets from Minish Cap.
TP's Castle Town especially right next to the band, Sacred Grove, Midna's Lament, The Forest Temple.
Skyloft Bazaar, Groose's Theme, Fi's Farewell, Earth Dungeon, Ancient Cistern from SS.
Song of Storms
Nayru's Song, Dead Pirate theme, Tarm Ruins and Dancing Dragon Dungeon are some of my favorites so far in the Oracle games.
Link looking for his sword, Tal Tal Heights, Mysterious Woods and the Face Shrine so far in LADX.
Gerudo Valley, Ice Cavern, Requiem of Spirit, Bolero of Fire in Ocarina.
Clock Town, Sword Master theme, Deku Palace, I liked Wood fall's theme but the wailing killed it, Goron Lullaby, Song of Healing, Stone Tower Temple, Final Hours, Oath to Order, Majora's second form in MM.
Even though I haven't played it Wind Waker Intro theme is so beautiful.