The problem is that there are different standards depending on the ships themselves and the venue chosen. Here on some random thoughts on my past experiences; in order from best to worst.
#1 Disney Magic. Outstanding presentation and the overall highest quality of any line I have been on. All venues were top quality, including room services & Palo for brunch. I liked the main dining room so much, that I was not able to try on other place at night.
#2 RCCL Vision & Adventure of the Seas. Both ships were outstanding in every way. Dining was one of the key highpoints of these great ships.
#3 Carnival Victory. While the ship was quite ugly and the pink dining room was horrendous: the food including room service was a cut above the others. It was a surprise for me; that a line with such tacky ships, can do relatively well in the food department.
#4 RCCL Enchantment of the Seas. Basically both food and staff were just above the mediocre mark, throughout the 8 night voyage. They really could have tried harder and been better. The Pay option Steakhouse; was truly a sad experience in all aspects.
#5 NCL Epic. The non-pay options were quite limited with both Taste & the Manhattan Room having the same set menu (both places had the same menu), that never changed or rotated. Pay options (Cagney's was outstanding!!) highly priced for what you got, what you would pay in Orlando.
#6 Celebrity Century. Grand presentations of small portioned food that was medeocer. Once grand experience that seemed diminished; though the brunch buffet (& room service) were the exceptions. The Specialty dining option; the Murono, was among the best dining in my Lifetime!!
#7 RCCL Monarch of the Seas. Like the Century, the buffet was the only reasonable dining experience aboard. The portions were so small in the main dining room that most people ordered two of every course. The the Indian section on the buffet was quite good.
#8 MSC Posea. What a shame, a most beautiful ship: with outstanding specialty dining (both the Japanese & Italian, were the best I have had on any ship) and great free ice-cream & pay gelato. However, it ends there sadly; with a gorgeous dining room and Buffet (which is the most attractive at sea. Unfortunately there is little food on the buffet (called the cafeteria) and the food in the main dining room is of a sad "European" standard. It is sad, but the food is an absolute deal breaker for this classic line!!
Its really odd, on RCCL there can be the same fleet wide menu; with completly different results depending on the ship. While one Holiday Inn should be the same as another, world wide; this is not the same at RCCL, in the food department. Even little things like ice cream which can for flavorless, (with no suger seemingly added) on the Monarch; can be outstanding on the Vision from Brazil. I guess the provisions are quite different based on region!