I prefer Celebrity over Princess but have never had your experience on any cruise….last Oct on Celebrity, meat in MDR was not good.
however, if you are traveling solo, that fact alone puts you in a different category for needs of stimulation, less interpersonal availability, and wanting to find some satisfaction in the food and/ or entertainment. Your post sounds like you where generally unhappy and the outside stimulation was not good enough. Period. That being said, I can understand Disney and maybe RCCL offers more for you. Try Oceania, lots of ports, good food, evening HH where you can meet others that just do not talk about assessing the ship.