We went on the Carnival Breeze over Thanksgiving last year and I found the free food options to be superior (other than the actual Thanksgiving meal, which is not surprising considering we all have the food we grew up with).
Guy's burgers, Guy's barbecue (though wife wasn't a fan but I enjoyed the bbq sauce options), the Italian restaurant was free for lunch and had an amazing lasagna, Iguana place that is like a Freebirds burritos, the omelet station, sea day brunch (amazing pancakes, fluffiest & likely highest calorie content I've ever eaten), etc.
Having done the three lines last year, to me the food quality order was Carnival, Disney and then Royal as a distant last place, and prior to kids we were loyal to Royal...in fairness to Royal it was the closest to restarting and you could tell the staff was struggling. We did do all specialty restaurants on Royal so that may have caused me to grade them harder since we were paying extra. Best meal was Johnny Rockets.