I have to say Iron Knuckles are my favorite, which is one reason I like Wind Waker. WW comes with something similar to Iron Knuckles, Dark Nuts. And there are a lot of Dark Nuts in WW.
Since I like challenging temples very much I particularly enjoyed the Water temple, which takes the first place. It is followed by the Spirit Temple (I loved the light puzzle and I was so awed when the statue's face melted)........[AAh recalls with nostalgia]
Firstly i just adore the music of the Temple.
I can easily listen to its music for ten minutes when inside the Temple.
It suits its music so perfectly.
And another thing is that you must change from big link to small link as each one can only do specific areas.
You have to use small link first as he crawls through a small hole after talking with Nabooru.
It also has a very Egyptian feel to it as im into things like that Pharoahs etc.
Forest. Definitely Forest. That's the best dungeon Zelda's ever had. The music, the poes, the layout, the creepiness, the twisted corridors...simply the best.
Forest because it has the most notable music, and I like Phantom Ganon. It's very twisted, Labyrinth like, and it's also the prettiest temple.
Even though I know this discussion is mainly about Ocarina, I've always felt like Majora's Mask's Stone Temple was insanely clever. And I'm a bit more critical of Majora's Mask as a Zelda fan.
The Forest Temple. It's got a great atmosphere to it, the puzzles were fun to figure out, you get the first taste of good challenging hand to hand combat with the Stalfos, and the Poe Sisters' paintings were a unique and brilliant concept. Then after all that, you get to fight Phantom Ganon, which is my favorite boss battle.