The two cruise lines I've been on that I've found to have the best food are Carnival Cruise Lines and Disney Cruise Lines.
Other Cruise lines I've been on had okay food and it was not terrible but not great either.
So in my opinion it's both Carnival Cruise Lines as well as Disney Cruise Lines that have the best tasting and best food on a cruise line.
It can all depend on your personal tastes as well but those are the two cruise lines I've found to have the best food.
Your food in the main dining room is included with the cruise line fare although some cruise lines have other food vendors that you can pay extra for the food from them.
I mainly ate from the buffet which was delicious.