Marin is my favorite. That's not just because OoA is one of my least favorite zelda games. The Ballad of the Wind Fish is one of the most nostalgic songs in the entire series. From when Marin sings it in town the the touching finale, it's really sweet and ever present throughout the game. It's also functional, being one of the songs Link can learn to play. Nayru isn't even around for most of the game, and I couldn't hum her theme if you asked me to.