Presidents week is a bit busy with the schools in the New England states on their week long winter break, Daytona 500 race - and YES a lot of race fans stay at Disney, and Twill Mania competition is at Disney. So be prepared for lot of girls to be staying at the value resorts and when that is full they will also book rooms at CBR.
Easter on the other hand would be a lot more busier because you have a higher percentage of schools and colleges on Spring break.
I would do Presidents week. I have done both and hands down Presidents week is better but colder. So pack accordingly. Remember Feb comes after Jan which is Florida's coldest month.
Oh forgot to mention that Easter is so busy they do close the parks because they have reached capacity and will turn people away. Which usually happens as early at 10:00 a.m.! That tells you that Easter is a busy crazy time to go. Last year wait times for Soarin were as high as 5hrs. that is right 5hrs!