I'd have to say, between the two 64 games, I liked Ocarina better. Majora's Mask wasn't bad, but it was really boring at points. The dungeon design especially was nothing like Ocarina's design. I loved every dungeon in Ocarina (with the exception of Bottom of the Well because it was hella confusing) but I found most of the dungeons in Majora's Mask to be tedious and boring, at best.
Don't get me wrong now, Majora's Mask is still an incredible game, just not as good as Ocarina, in my book.