There are 6 attractions at Disney's Hollywood Studios we rate as "Not To Be Missed":

Not To Be Missed at Disney's Hollywood Studios
Echo Lake Star Tours: The Adventures Continue
Muppet Courtyard Muppet*Vision 3D
Pixar Place Toy Story Midway Mania!
Sunset Boulevard Fantasmic!
Rock 'n' Roller Coaster Starring Aerosmith
The Twilight Zone Tower of Terror

Not To Be Missed Attractions at Other Parks