Start to finish, I still think the best attraction experience is Tower of Terror (at HS of course). But, Radiator Springs Racers was really great. To me, it was more than just an upgraded Test Track. The ride seemed so much smoother, and the theming was incredible. The entire theming of Cars Land is just incredible. The best "land" in all of Disney to me (disclosure, I have not yet been to AK since Pandora opened). I felt like someone had dropped me right into Cars the movie when I entered that land.