Earthbound/Mother 2

Earthbound (Mother 2 in Japan) is one of my favorite RPG's of all time. You play as Ness, a young boy who is gifted with psychic abilities. When a meteorite crashes beside his house in the quiet town of Onett, it is the beginning of Ness fulfilling a prophecy written on an apple. On the journey, Ness must befriend two other young boys and a girl who will accompany him in order to save the world from the evil Giygas.

Giygas is the embodiment of evil. He is practically evil itself. His very presence corrupts good people into raging lunatics. Friendly animals become ravenous, attacking at will. Monsters terrorize small towns. And when you make it to Giygas after traveling the world, you might expect to see a hideous monster. But no. He is without form. You cannot even grasp the true form of his attacks! The game flat-out tells you this while you're fighting him. Without spoiling the ending or boss fight for anyone who hasn't played this game, I will say that the final battle makes quite a bold statement in how evil must be defeated.

The dialogue throughout the game sets it apart from almost every other RPG I've played. It is humorous, witty, and enjoyable throughout.

And the music is fantastic. Check out this boss fight music if you want to hear just how great the soundtrack is:

http://starmen.net/mother2/music/044-%20Earthbound%20-%20Sanctuary%20Guardian.mp3