All the other parks will also be crowded. Just be sure to stay away from Magic Kingdom on Easter Sunday. At MGM, try and watch the second showing of Fantasmic -- I believe it starts at 10:00 and the lines are not so bad. For the first showing, they line up two hours ahead of time.
At Epcot, we always have to grab a spot for Illuminations at least 1-1/2 hours ahead. Animal Kingdom is always crowded, but the crowds are lighter in late afternoon. Just plan ahead and you should be fine. We go every year at Easter, because of school break.