For pure fun and repeatability it would be Buzz Lightyear. We also do the people mover many times but that is more for relaxing and slowing down. The sentimental favorite is COP but we would not do it more than once or twice if it would ever be open when we are there. Been there 4 times in the last few years and it was only open the first time in Feb 2001. Even late June 2003 it was closed.
Chuck