We have been on ten cruises--nine Princess and one Holland America. We loved them all. The food on HAL was marginally better, but we are not really big food people, and the room was marginally nicer, which we enjoyed.
We liked the people we met better on Princess. The people on HAL seemed really, really old, but that may have been because it was the beginning of a really long cruise.
The only way we will know for sure about Cunard is to give it a go. We are pretty confident that we will love the dance floor and the music, and that is the most important thing for us.
If we love it madly, we will try to put together a group of our dance friends to join us next year for the 5-day Independence Day cruise. I will write a full report.