Have to vote for Space Mountain. The pitch blackness is what elevates the fear and excitement a little more over Rock n' Roller Coaster. I'm always afraid I'll get hit in the head by a beam or something on SM.
My favorite ride last time i was at Disney in November was Rock N Roller Coaster. I was nervous the first time on but after that it was so fun. Me and my mother would pose for the picture they take at the beginning and i would sing the Aerosmith songs on the ride. My second favorite ride would be ToT.