First of all both ships are very nice.,,,but Disney is definitely geared towards families. I will have to say I enjoyed Allure so much more then the Fantasy. I guess the main things to compare are the ships, food, cabins and kids clubs.
Ships:
Both ships are in fact amazing. New clean and pretty awesome! I liked the pool area on Allure more then Disney. The Allure has four pools which makes crowding less likely. But Disney has the little water park in the shade and THAT was awesome to let the kids play without being in the sun.