I seriously believe zelda: link's awakening to be the best game of the original gameboy.
At the time it got out, it was so much more advanced design - wise from most of the other games, it was unbelievable.
It was also my first zelda, and the first action adventure i played, and i think i cried in the end, it felt akin to reading/watching lord of the rings, a great journey, a real adventure coming to it's end
Second favorite is the original wario land, cause it was such an ingenious turn for the series (from the fluffy mario games to the bad - ass wario universe), featured a really smart reward system at the end (remember the multiple things the jin built for you depending on the treasure?), and i thing it was one of the last great games Yokoi headed