Well it does depend on what you enjoy the most, but I don't recomend AK since it just doesn't have enough to take up a full day and is only open until 6:00.
It depends if you have ever been there before. Even as a adult I don't feel like I have been to WDW with out at least one day at MK, so I would do MK and Epcot.
MK has tons to do, a new firework show, lots of atractions. Also tends to be the most crowded. Many of the atraction are ones kids and children can enjoy, but are classic atractions. Mickey's Philharmagic is new. Lots and Lots of Disney Magic. A trip to WDW is not complete with out seeing the castle.
Or there is Epcot and MGM, Either way I am thinking Epcot at least one of the days (something for everyone, lots to do, Misson Space and World showcase, no other park like in on Earth.)
MGM has RR and TT, both are thrilling. Some good shows, fantasic is good, but it doesn't seem to have as much at Epcot and MK.
It really depends on what kind of a person you are, what your likes are. Also if there is any sit down restants you want to hit.
Have a good trip.
Make sure to take another one in the future for at least a week to see it all (or closer to it all.)