The CPU AI in CTR NF is impossible to play against. Anything less than a perfect run in Story Mode will cause you to lose the race (classic mode). Frankly that saps a lot of the fun out of the game.
I have only played MK 8 a few minutes but I assume it is at least fair.
http://www.youtube.com/watch?v=F1gWECYYOSo
Please Watch/Share this video so it gets shown in Hollywood.