If those are the only two choices, clearly Ocarina. Great story, large area, takes considerable time to finish, good weapons and enemies to mess with, and you really can work at exploring.

Majora is a turd. Far shorter, a higher pressure game with the timer(which eventually you can to a point manipulate), you lose some bits of your work and effort each skip back in time, pressure to finish areas before the time expires, story isn't as interesting at all...it's just not fun and a lot of the masks are just a burden and uninteresting.