The best Mariokart is MarioKart: Super Circuit for the GBA.
I've spent many hours playing the 64 version with friends so it'll be near and dear to my heart always (so much drunk driving*), but Super Circuit had it all - The tracks, the tight controls, and the lack of terrible items.
*Drunk Driving is a game where all the contestants start off with an unopened beer. The objective is to finish your beer before winning the race. You cannot drink and drive at the same time. If you want to drink, you have to put down your controller and start chugging.