Majora's Mask by a land slide. For those of you who have not finished MM, get off the Epona and finish the game...
It was glorious and 3 times larger in mass then OoT landscapes. I'm sad that this Zelda game was released during the worst time for Nintendo's history (During October 26th, 2000) right next to the PS2 launch
I enjoyed Orcarina of Time for a long time, but I avoided Majora's Mask since it's release, but last year 2004, I finally finished it, and I was blown away at the depth of this bizarre unique game.
Images and animation being pulled off on MM that OoT could not possibly do.
Do yourself a favor, as a Zelda fan, you got to finish it!