If it's from Ocarina of Time I'd say the Forest Temple and Water Temple. I just liked listening to the Water Temple music while I thought the Forest Temple was fun to listen to. I also like the Spirit Temple theme.
The original Legend of Zelda had the best dungeon music in my opinion. It is the only dungeon theme that really sticks in my head. The sandship from Skyward sword also had some good music too. Dungeon songs arn't really important. What matters is the location and character themes. Fighting themes have to be done well too.
I loved the Spirit Temple music. By far the best. Ganon's Tower is a close second. I like the organ music and how it gets louder the further up you go. Letting you know that you're almost there.
Without a doubt, the Forest Temple; the use of sound effects and atmoshperic noises was excellent and the vocals (ish) added a level of erieness and franticness to the song.