Most of these come from the Wii and/or DS games, so keep that in mind. Although I have played almost every single version of the game, I am most familiar with MarioKart Wii and MarioKart DS.
12. Waluigi Pinball
I love real pinball, and it's even more enjoyable in the form of a race. This course is action-packed and so much fun!
11. Delfino Square
More casual than Waluigi Pinball, I love the graphics of Delfino Square, especially the rainbow bridge.
10. DK Mountain
This complex course takes place in the middle of a jungle. I wouldn't recommend it for beginners, but you can really love it once you master it!
9. Frappe Snowland
This is a classic MarioKart raceway. It first appeared in MarioKart 64 for the Nintendo 64. Be careful not to slip and slide on the ice or end up in a snowdrift.
8. Donut Plains 2
A simple classic that resembles the average "World 1" in the Super Mario Games. Save for a couple of difficult turns and a lake in the middle of the course. This is an easy and relaxing race track.
7. Mushroom Gorge
Bouncing on the mushrooms is half the fun of this course, but be careful not to fall off! This game first appeared in the Wii version of the game, and it still delights me to do tricks and flips in the air as my player character jumps on the green and red 'shrooms.
6. Coconut Mall
This course takes place indoors but still has an overall tropical/beach setting. Be careful to go on the right elevator, and don't get hit by the Miis driving cars outside of the shopping center. Besides that, have fun because this is a very adorable race course.
5. Bowser's Castle 1
There have been so many Bowser's Castles in almost every single Mario Kart game. After all, what's Mario without Bower's Castle? I'm going to have to choose a classic Bowser's Castle as my favorite here. This particular version was first found in the SNES version of MarioKart. Much like the castles in the Super Mario games, you have to be careful to avoid the not-so-friendly enemies and the lava.
4. Maple Treeway
The cannon is the best part of this raceway, no question asked. The fall graphics are very stellar; there's something amazing about driving through trees and piles of maple leaves.
3. Wario's Gold Mine
Having an almost roller-coaster vibe, this intermediate course is another great staple of Mario Kart Wii. Watch out for the bats and don't fall off the track. Most portions of the road have no guardrail to prevent you from falling over the side.
2. Koopa Cape
If Wario's Gold Mine reminds me of a rollercoaster, Koopa Cape reminds me of a waterpark ride. If the name doesn't give it away, Koopa Cape is set on an island. You get to drive underwater at one point, and for the rest of the course, you're driving either directly through a river or on a path right above it.
1. Rainbow Road
A super fun yet super frustrating course. When people think of MarioKart, Rainbow Road is typically one of the first raceways that come to mind. Think about all of the times you've played the game, only to fall off the edge and go tumbling towards the earth! The only thing better than a pixelated Rainbow Road would be a real rainbow road rollercoaster (try saying that really fast) at a theme park!