Personally, I think that Alien Encounter is the scariest.
DD, who turns 9 the end of this month loves Splash Mountain, Big Thunder, Space Mountain, Test Track, RnR, and StarTours.
She is iffy on Dinosaur.
Thinks that Body Wars is too rough.
And absolutely won't go near ToT.
She has never expressed a desire to do Alien Encounter, and I really think it would freak her out!