You know, I wanted to pick Majora's Mask, because in several ways I do consider it superior to Ocarina of Time. But, Ocarina has more sentimental value to me. It was my first console game on my first console (Up to that point I was all PC and Gameboy), and I have many fond memories of me playing it, so, I have to go with that as my favorite.
Though, I've honestly yet to play a Zelda game I didn't enjoy, so I feel like picking a favorite implies I don't like the others, which is far from the truth. But I guess if I could only have one, I would pick Ocarina of Time.