I don't know how anyone could say that the food on Carnival is that much better than Royal Caribbean. I have been on ships from both fleets and would say that the food is fairly comparable. If you put a gun to my head and forced me to choose one as being better, I would give a slight edge to Carnival.
As far as paying for food...both lines have specialty restaurants that you can pay to eat in. The only difference that I know of (and this may have changed) is that now, in the main dining room, Royal Caribbean now makes some of their finer main courses from the specialty restaurants available for an extra charge. You do not have to choose that option and you can still get the same great menu in the main dining room for free. It is a shame that people have twisted this to mean something else for propaganda purposes.
All in all, I have found Carnival and Royal Caribbean to be quite comparable. If you like the massive mega-ships, then Royal Caribbean wins, however, if you like the ultimate value with a slightly larger stateroom for less money, then Carnival wins.
Good luck and let us know how you feel after you return. Just do yourself a favor and don't go into it with any preconceived notions.
Have a great cruise!