If I had to goto only 3 parks, i'd pick epcot, magic kingdom, and hollywood studios.
Don't get me wrong, expedition everest, finding nemo: the musical, dinosaur, kali river rapids, and kilimanjaro safaris are in my top 25 disney attractions, but Beauty and the Beast, Indiana Jones Epic Stunt Spectacular, Lights! Motors! Action! Extreme Stunt Show, Muppet*Vision 3-D, Rock 'n' Roller Coaster, Star Tours: The Adventures Continue, Studio Backlot Tour, The Great Movie Ride, and The Twilight Zone Tower of Terror tip the scale towards DHS by 0.001%