Since The Wizarding World of Harry Potter opened in 2010, you'll want to definitely make Islands of Adventure your top pick. Plus, The Amazing Adventures of Spider-Man opened in brand new H-D and the park has been painted and spruced up a lot since 2009. In Magic Kingdom, you'll find the new Fantasyland, which I'm sure you've heard about. Plus, if you have kids this would probably be top pick.
If you return in a few years, I'd place Universal Studios Florida at the top of the list. They have a lot of major expansions happening that will make this park probably one of the best in the world (as if it isn't already!). There is a Simpsons expansion, Transformers the Ride, and a major Harry Potter expansion all taking place at once. Plus, if you don't go this visit, you wouldn't have seen Despicable Me: Minion Mayhem, Cinematic Spectacular, Super Star Parade and (depending on when you last visited).
If your family like coasters and haven't been on Manta then try SeaWorld or Busch Gardens as they have Cheetah Hunt now. I love Animal Kingdom and Epcot but nothing has really changed since 09 (I mean Test Track got updated but it's hardly a major draw). Magic Kingdom has some of Fantasyland open now, but you might want to wait until it's all finished.
Depending on when you go, you might want to consider Aquatica Water Park. This is my personal favorite water park. We always have a blast there…
If it is too cold for a water park, I would consider Animal Kingdom.
Have a safe Trip..
Walt Disney World's Magic Kingdom
Disney's Animal Kingdom
Disney's Hollywood Studios
Disney California Adventure
Universal's Islands of Adventure
Universal Studios Florida
Universal Studios Hollywood