We just got back (Sept 20 - 27), and I'd say for me none would be 1/2 day, but that really can depend on what you want to experience.
At AK, you've got FOP, Safari, Rapids, Everest, Dinosaur, + all the Shows (which we didn't even see), not to mention the Tiger and Gorilla walks. And the Architecture in the Areas of Africa and Asia, down to Wires hanging out of electrical boxes is wonderful.
HS offers 3 rides in TSL, Millennium Falcon, Star Tours, ToT and RnRC, + a show or 2.
MK definitely not a 1/2 day.
Epcot, I love the WS, and with Int'l Food and Wine we could have spent so much time (and money, ha ha) just strolling and people watching. My regret is we didn't take as much time to just "stroll".
It really depends on whether you are just going to do Rides, and/or experience more than just that. Admittedly, I find it's difficult to not do Rides, slow down and just take time to enjoy some of the simple things. For example, I really enjoyed early a.m. at MK just having a Starbucks coffee and sitting at Casey's at an outdoor table listening to songs like "The Trolley Song" (from Meet Me in St Louis). I'd love to go during Christmas Decor, and just "soak" in the atmosphere (well, and do some Rides Too).
My goal is to just SLOW Down and Enjoy, Plus, I'm getting too Old to enjoy the Rides I use to ride back to back, i.e. Expedition Everest.