I have been on both the Disney Magic and Wonder and just went on Royal Carribean Freedom of the Seas last week.
To answer your comparison questions:
Disney has great crusies that are timeless and has nothing to worry about. FOS is the biggest ship in the world, and has all the cool new stuff but is not necessarily better.
Disney likes:
We liked the kids club at disney way better (7yo son and 10 yo daughter), we liked the rotating restaurants for dinner better, we liked the room size better, we liked the chicken fingers better, we liked the pool slide (FOS has no slide), we liked the beeper system better, Palo was better than Chops, we liked the Disney characters, better bathroom in the cabins, better night shows, better Interent connection, free Coke stations.
Freedom of the Seas likes:
Flowrider is the best activity on any boat, H2O zone is awesome, better pools, ice skating rink, casino (beware of smoke), awesome promenade, incredibly large boat, better arcade, better for older teens and college crowd, better drinks, this is a floating city and we did not feel the boat rock as much as the Disney boats did, better LCD tvs in the rooms.
There are more comparissons, but this is a brief overview.