Star Tours, The Haunted Mansion, Pirates of the Caribbean... and, heh, two of my personal favorites, The Enchanted Tiki Room and The Carousel of Progress.
I really, really love those two because, for me, they really embody the spirit of the mid 20th century and the optimism and fun Walt Disney had about the world. It reminds me of when I was a kid, and I loved the "early" Walt Disney stuff. He had a direct hand in making those attractions, and the Carousel of Progress is the only attraction he ever really touched in WDW. I've definitely got a little hero worship for Walt - he's been an inspiration to me since I was a kid, and I could ride those rides all day long, singing along to myself. Who am I kidding - I sing "Great Big Beautiful Tomorrow" to myself practically every day.