It's been years since I went on Carnival, but I did like the food in the MDR better on Royal, but I have to say I haven't been impressed with MDR food on RCL lately either. IMO there are far fewer rowdy children on RCL.
However, I did like the late night food options (Guy's burgers, etc) better on Carnival and their on deck movies were good as well. I don't like watching the movies in the aqua theater. I prefer Carnival's screens on the pool deck where you can sit in a lounger with a blanket and (free) popcorn.