My favorite dungeon would have to be the Fire Temple, mostly because Volvagia is awesome. I also like fighting Lizalfos a lot, and the hammer is freaking sweet.
The Spirit Temple had great design and great music. It had my favourite boss battle in the game in Twinrova, and i loved the concept of returning there as a child.
I voted for Jabu-Jabu's Belly since the question was favorite temple to beat, and I love beating that dungeon because then it's time to become a man, which is the best part of the game.
My favorite temple to beat in Ocarina of Time is the shadow temple. I always liked it alot because its pretty special considering you have to go through fake walls and deal with scary/freaky monsters. The boss fights is really cool aswell.
I've almost always like the desert dungeons in Zelda games (aside from ALttP) and the Spirit Temple was always my favorite one to go through. There's a bunch of cool details you can find from looking around and all and it's awesomely cool.
I liked the Spirit Temple the most. I loved the theme of the temple, the music and the boss. The puzzles were quite good also, and I liked the idea of doing the temple as Young and Adult Link. One of my favorite dungeon in the series. I also really enjoyed the Forest Temple and the Shadow Temple.
Either the Forest Temple or the Shadow Temple. I guess I like the dungeons with a creepier vibe to them? The Water Temple would be my second favourite because it's fun. I love the Shadow Temple because I like all of the invisible platforms and all that, it just feels great. The Forest Temple has always been one of my favourite dungeons, because out of all of them, it has the best atmosphere in the game and for me it was just such a great achievement to finally get there the first time I played. Also, it has the best music.
Forest Temple by far. The music, the atmosphere, the dungeon item, the boss battle, the poes, the numerous themes, everything is memorable from start to finish. Oh and the Stalfos. Stalfos are by far the best enemy in OoT with Iron Knuckles in a close second. The Shadow Temple is in a close second for me.
Believe it or not, the Water Temple is my favorite to beat (which was done on the Special Edition, btw). It wasn't only for the sake of getting out of there--though I'll admit, partially it was--but the challenge of solving how to get to different areas of it somehow carried me through. While I did end up using a guide for most of it I tried to navigate the labyrinth without logging onto whatever site helped me (I believe it was GameFaqs). But I thoroughly enjoyed the Miniboss battle with Shadow Link, a character who I deem is lacking in appearances. Then there is also Morpha, the perfect trial to finalize my experience in the WT. Defeating that gelatin Boss satisfied me greatly, credibly because it was accomplished it with a half-broken Gamecube controller.