Haven't played anything beyond Mario Kart 64, so half of it I don't recognize (and I don't remember any battle courses from Super Mario Kart because I never got the chance to play it with friends).
That said, Toad's Turnpike is definitely memorable. Driving on the mirror track was one of my favorite pasttimes. Yeah, hard as heck, but also exhilirating because it's the ultimate test of skill. Maybe it was a precursor to "Burnout" for me. But I agree the track's pretty straightforward. All you really have to look forward to is weaving in and out of traffic. Why can't I skid to the right and cut off a car, or jump down a steep incline and hope I don't hit a bus along the way... or have one section of road dealing with crossing traffic (kind of like Kalimari Desert but with multiple trains).
Wario Stadium, yes. As I believe the second-longest track in Mario Kart 64 (when you don't take shortcuts), and containing that famous jump where a lightning bolt timed just right will screw over opponents, it's a favorite. Also, in hindsight it does have some tall sections and rough turns. What annoys me is that the shortcut is so well known that you can hardly find any videos anymore of people playing the track the normal way. What's the frickin' point of playing Wario's Stadium if you're going to use the shortcut? That's even in a tournament video on YouTube, they allowed shortcuts just because everyone agreed to it. Well, the stadium's no fun that way...
Yoshi's Valley, heck yeah. I initially sided with it because of Yoshi in the title, but it's also a confusing track at first, and pretty fun once you realize you can take multiple paths. Of course, that means you'll soon find the optimal route and use that exclusively, but it's still a blast.
Rainbow Road... I do appreciate it since it's the last track in each game, the longest (save for the first game perhaps), and usually the hardest. In the first game it at least had that intimidation factor. No walls anywhere. But in the later games there were walls and it was all cutesy... candy-coated vomit-inducing fluff. Ok, not quite, but it had happy music and just seemed to lose that special quality that made me fall in love with it in the first game.
I'd vote to include Royal Raceway and maybe Donut Plains 2 (it's all peaceful and then the moles mess you up)... maybe Kalimari Desert too, we just always seem to remember that train. But I don't understand why sometimes the train would be shorter than normal.
