Sky-Kitsune
Smash Apprentice
After seeing the first few screenshots of it, I thought the simple layout seemed pretty boring, but then I really warmed up to it as soon as I saw videos of the stage in action. As far as visuals go, I really couldn't of asked for more. I love how checkpoints appear randomly, and characters from the Sonic fanchise do the loop in the background, which also fits in really nicely with the layout.
Green hill in action: http://www.youtube.com/watch?v=wu1xGl3JRtI
Just to note: Tails, Knuckles and Silver all do the loop in the background occasionally. Skip to 1:30 seconds in this video, all three characters interestingly do the loop simultaneously: http://www.youtube.com/watch?v=KR83t02JY5E