Ouff, this is difficult.

To me it’s a very close call between:

• Majora’s Mask (atmosphere, inventiveness with the loop, boss battles)
• Link’s Awakening (first self-owned game, lots of memories, also that nerve-wrecking final battle with forms after forms after forms)
• Tears of the Kingdom (the way they hid the third world until release, the grand atmosphere, the whole thing around the Master Sword)

Majora’s Mask probably wins. But it’s a really close call.