Totally agreed with Majora's Mask. Why? Everything you see in the game is sadness and death. Here are very important examples: 1.-Termina is related to the words "End, Doom, Death and Despair", 2.-If you fail, the moon is gonna fall and destroy everything that exists, 3.- This is the less important, I really cried when my counterpart went to the other world when healed... So sad.
Majora's mask hands down. Throughout the whole game there is an overbearing feeling of hopelessness and sadness emanating from all the inhabitants of Termina. Although in TP the game had a similar sad feel it did not share the same hopelessness. The bottom line for me is that Ganondorf is not a sadistic being who commits terrible crimes for no reason at all. Everything Ganondorf did was to benefit him, while Majora simply wanted to end civilization and take as many lives as possible for the enjoyment of committing such an act. That is why MM is much darker than TP, because the chief evil is an insane being who does not think and process things rationally.