Uh, yeah, this is what we call here a "squash match".
Mario Kart Wii is a successful game, but that's mostly due to the Wii's enormous kiddie and family audience and its huge hype. This said, it's a good little racer, with a lot of tracks and good online capabilities. I mean, it's a decent Kart game, but its been outdone by several titles in its own series, and it can't even hold a candle to its competition here.
Enter Kingdom Hearts, generally agreed upon as in the top 20 or better of best PS2 games of all time (a stiff field), possessor of awesome gameplay and rockin' graphics. Stellar visuals, score, voice acting, and gameplay, which blends the adventure and RPG genres beautifully. It has great combat and good AI for your partners, and becomes an awesome crossover RPG with its mad blending of Final Fantasy and Disney, which shouldn't work, but it does. Brilliant story in general. Not to mention its huge financial success, with over 5 million copies sold worldwide. Yeah, this is a fantastic game, and it outclasses Mario Kart Wii in every way, shape, and form.