I have been on all 3 of the ships in question
I will start by stating the
RCCL and
DCL are my favorite cruise lines... however with that said I will NEVER go on Sovereign of the Seas again. It may have just been a fluke (you know how 1-10 has a bad time) but we had the worst vacation ever on the Sovereign. The rooms are the size of a closet on Disney, the crew was rude, the shows were horrible and I think the worst part was that I had choosen S.O.S because we had already done Disney (which was my hubbies first cruise) and decided that my husband needed something to compare DCL to (boy was I wrong). We spent most of the trip docked next to the Wonder with me sobbing that we could have been there. Again I am a firm believer in the vacation fact that at least one person will have a bad expereince and not everyone one the same trip will feel the same so I know there are people that think S.O.S is the best ship ever, but I am not one of them. The food was good and the private Island (Coco Cay) was nice, but that is about all I have positive about that trip.
Carnival Fantasy also has rooms the size of Disney closests, but the cruise was fun for cheap. If you go into Carnival without HUGE expectaions you will not be disappointed. The ship is Hookie (kinda frilly, lots of neon and crazy design patterns). the rooms are small (or at least they seem small) and the atmosphere is more "party" but we had a great time for the money we spent on it. Again knowing it was Carnival and it was cheap I did not have huge expectations, so I was not dissappointed, but it definetly was not Disney.
My choice for you would be Disney. The rooms are nice (and spacious), the crew is definetly up to Disney standards, the food is good and the ship is beautiful (very well decorated and themed). I am a firm believer you get what you paid for and Disney may be more expensive than the others, but it is definetly worth the extra money. I would not worry about Disney overload, the Disney ships are very well done. Even having just done Disney I don't think it will overload you. Yes there are characters around and the Disney themeing, but it very nicely put together and not "in your face" I feel it is subtle and just a really nice relaxing vacation option
Check out this web page:
http://www.cruisesonly.com/c/cruisemain.asp
they have 360 degree views of the different cruise ships, public areas as well as room categories. Click on the crusie line you want, the ship you want and then on the right it says photos and tours, You can look at S.O.S, Fantasy and the Wonder and see what you would be booking, which also may help you with your decision.