In no real order:
Country Bear Jamboree - a true classic that a lot of people don't seem to appreciate. Good old folksy fun, great music loveable characters, and some of Marc Davis' best work. Not to mention a MK original.
Carousel of Progress - said to be Walt Disney's favorite attraction, it's nice to know that the show that would never stop turning still does in the Magic Kingdom, even though it's been moved around and changed a lot.
MuppetVision - absolutely hilarious. It does a brilliant job of merging screen and Animatronic, and Jim Henson's style translates really well into a live setting. I love the comedy, the chaos that ensues, and all the great quotes ("a salute to all nations but mostly America").
American Adventure - arguably the most epic and sophisticated show ever made with an all-Animatronic cast, and it makes a real case for the medium's potential as a serious art form. It's a great counterpoint to Spaceship Earth (American history vs world history) and I force my family to watch it every time we're in Epcot.
Maelstrom - for me, one of the great Disney dark rides, even though it's seldom ever listed as such. By Disney comparisons, it's delightfully dark and moody, and I love how the boat is altered by the ride environment (trolls, waterfalls, etc.). Just the right amount of thrills, fun, and the feel of those fairy-tales from the far north.
Gran Fiesta Tour - a lot of people complain about the toonification of Epcot (self included), but this is one ride that does it right. It keeps the great set pieces and general feel of the original, but removes most of the cheese factor while adding a healthy dose of fun, all while staying in-theme. I'd say it's just as good as the original, as someone who clearly remembers both.