Ocarina of Time is the best complete Zelda package. It has the gameplay, the dungeons, the items, the feels, the direction. If the Water Temple was a bit more straightforward and didn’t have that fight with Dark Link, nobody would remember a single bad thing from OoT. I guess the PC recompile with 60fps and free camera fixes the only real couple of technical issues the game had and that make it a bit hard to go back to these days.
Majora’s Mask is a more complex and demanding game, but it rewards handsomely whoever has the patience to learn and understand it.
It is a stunningly mature game disguised as a fairy tale for kids - just like the fairy tales of old. It takes the premise of Groundhog Day and builds a tremendously dark story around it. Solving every NPC storyline in MM is incredibly rewarding and creates a real connection with the game’s world and characters. You really feel like you did some good for these people, even if you’re still to solve the greater threat. MM punches above and beyond most realistic, cinematic games that came after it. But yeah, it’s not easy to get into.
Both games are amazing. OoT is just the most straightforward of the two. It’s a game that really everyone can enjoy, as long as they’re not so jaded that they absolutely need real people and real(istic) environments to enjoy a story.