Sorry, the DS version is the only one I haven't played. I've only played the GBA version for a few hours total. The others, however, have seen me at the controller for an absurd amount of time, either by myself or with a group of friends for an entire evening. I've probably said this before here, but in college, a few of us literally failed midterms because of Mario Kart 64. It was dangerous. We would play through the entire evening.

I strongly recommend that if you haven't tried it, pick up Double Dash. It took me a long time to get used to the "two players per kart" thing, but that game is a joy, and should be pretty darn cheap these days. I'm hoping that I'll adjust to MKW just like I had to with Double Dash, but I have entirely different problems with this game.

*edit*
On the whole, my favorite Mario Kart is still the first one. It doesn't hold up all that well anymore, but I still think that game had the absolute best battle mode. It was perfect, IMO.