Hello...My wife and I have cruised RCCL, Princess, and Carnival. We will be taking our 14th cruise this October.
We think that all three lines are very good. Never have encountered a problem. This is just our opinion for what's it's worth, but we both feel that RCCL is a bit more upbeat than Princess and appeals to a wider range of age brackets. We love RCCL.
We also love Princess. We like Princess when we want a cruise that is a bit more subdued. We have noticed that there are more older adults and things aren't as wild. Plus, we just love the Wheelhouse Lounge.
Carnival was fine too, however, it seemed like it was for young and young at heart people who just want to party all the time and never rest, which is fine.
As far as food, entertainment, the crew, the rooms, etc, we think all are great. Bottom line is your personality. Every person is diferent and expects diferent things from a cruise line. If you go on RCCL I do not think you will be disappointed.
Hope this helps.