Oh wow, let's see... I guess I can tell you what my favorite tracks where.
Super Mario Kart:
I have not played this in forever, but I definally remember the good times when I played this. I have several favorites for this one, but the overall favorite track(s) would be Koopa Beaches, Chocoland Lands and, of course, Rainbow Road.
Battle Stages:
Agh, which one was it...? I think it was Battle Course 3 that was a beach theme. My memory is a little fuzzy on that, but I always played with my brother on that stage.
Mario Kart 64:
I have this downloaded on my Wii and I played it to death on the 64. I can go on and on with this, but I would just bore you (if I haven't already). *shot* But anyways, I really did like Toads Turnpike because that you were driving in traffic. Rainbow Road was fine, but I found it too easy. But I loved Wario Stadium because of how big it is and how fun it was to jump the wall to get a jump into first. =P
Battle Stage:
Block Fort and the Double Deck stage (I think that's what it is called, but I won't worry about it). Spent most of my battle time on those two. Sky Scraper is boring to me, but still fun to launch your foes into the pits with a red shell.
Mario Kart Super Circuit:
Never did play this one... But while playing the Retro Stages on Mario Kart Wii and DS, I have to say that Sky Garden is my favorite.
Battle Stage:
Never did play any of them.
Mario Kart Double Dash!!:
Oh wow... This one was pretty fun. I really have no favorite stages on this, but the Sherbert place (again, don't know the name of the stages) was pretty much the only stage I liked.
Battle Stages:
Most of these stages were too crampped to me... Pipe Plaza was pretty much the only one I would play on.
Mario Kart DS:
I spend HOURS playing this, even on Wi-fi! The only thing that annoyed me was the snaking... But I learned how to snake myself and end up with a broken R trigger. >.< My stages were Wario Stadium, Air Ship Fortress, Tick Tock Clock, Shroom Ridge, and Rainbow Road.
Battle Stages:
Blah... These were pretty boring. But I suppose Twilight House was decent.
Mario Kart Wii:
I still play this today. I would have to say that all of stages were my favorite. But if I have to pick one, it would be Koppa Cape. The music on the stage is fun and really up beat. =P I find myself fighting to get that stage on Wi-fi, until I got tired and just went random.
Battle Stages:
The only decent one I would play is the new Block Fort, and maybe Funky Stadium. If It is coin battle, it is Cookie Land. Why? It's small and when you get enough people to play it can be really chaotic. xD
Mario Kart 3DS:
*Shot for the game not being out yet* x.x;
But yeah, that is my list of favorites.