Honestly, I liked them both. The Disney Wonder is just such a magnificent ship, but there are some perks to cruising with RCCL.
For example - they have buffets for every meal, plus midnight buffets even on the 3 nights. The food was excellent and there was always a huge variety. I wasn't as thrilled with the food on DCL. In my humble opinion, RCCL's food was better. Also, if you are into it, RCCL has a casino, which is always fun late night. Throwing a couple bucks into a slot machine and coming out a winner - that's fun to me. Though I don't mind that the
Disney cruise doesn't have a casino.
RCCL has its own island, Cocoa Cay, which is MAGNIFICENT. I can say that I think that it gives
Castaway Cay a run for it's money. My only problem with it is that you have to be tendered in and with a toddler that wasn't too much fun, I was scared the entire time on the tender, so it is nice that Disney docks right up to Castaway Cay.
If you are traveling with a toddler, I'd say Disney is your best bet - there is more for them to do: Mickey's ear pool (they can't go in any pool on RCCL) and Flounders. There is really not much for kids under 3 to do on RCCL. For the most part, I had to make my own fun for my son which wasn't a problem, but there was no service like Flounders on RCCL if I wanted to take a trip to the casino or one of the clubs, whatever. For kids 3 and up, there were a ton of activities.
All in all, I will probably continue cruising with Disney, but love knowing that I can flip over to RCCL and still have a great time especially if Disney's pricing continues to go through the roof!