Hardest dungeon of each game, IMO:
LOZ - Level 9
ALTTP - Tower of Ganon
LA - Eagle's Tower
OOT - Water Temple
MM - Stone Tower Temple
OOA - Jabu-Jabu's Belly
OOS - Shield and Sword Maze
TWW - Wind Temple
TP - Lakebed Temple
PH - Temple of the Ocean King
ST - Tower of Spirits
SS - Sky Keep
ALBW...
ALTTP - Tower of Ganon (final dungeon)
Link's Awakening - Eagle's Tower (#7)
Ocarina of Time - Forest Temple was tough for a first temple. Water Temple took me forever but it was more confusing than hard.
Majora's Mask - Stone Tower Temple wasn't hard but I needed to reset for more time.
(Have...