We go to WDW 1-2 times a year. We always go Christmas week or Easter week. I am a teacher so it is holiday breaks or nothing. We have gone in the summer but it is to hot for me.
Easter - Busy, great weather, flower and garden festival is wonderful.
Christmas - Busy, decoration are great, weather is hit or miss.
Personally I love
Christmas at WDW. The magic of the holidays make the crowds seem more managable. People seem to be happier at Christmas.
I know it is busier at Christmas but personally I thing Easter "feels" more crowded. I think the difference is at Christmas you have all the decorations to distract you. We spend more than one night just checking out the great decorations at Epcot and catching the different Santa shows in the different counties. At Easter it is more rides so it seems like more waiting to me.
Either way have a wonderful vacation - you can't go wrong with a WDW trip.
This year we are booked Dec. 22-29, 2012 and March 27-April 5, 2013. We already have airfare purchased for both.