Mine is a toss up

Mario sunshine (gc) after the wonder that was Mario 64 - they unleashed a game were you clean the streets (WTF)

Duke Nukem 64 (N64) - One of the best FPS at the time and I thought yerrr great 4 player split screen this will rock - "Hail to the king baby". Not only did they pull the 4 player option down to two they removed the blood, the swearing and the boobies - I sorry I`m not playing the same game any more. This was more like "Err I have something stuck on my boot"