Our friends who have been a loyal X customers for over 10 years just returned from a cruise on the Equinox after not cruising for 3 years, and were so disappointed. The food, the entertainment, the activities, the demographics - they didn't like one single aspect of their cruise.
O is in a different league. Yes, the entertainment is low key, but entertainment on X is also not what it used to be. Plus a much better food, no crowds, no lines, everyone is treated the same regardless of their cabin category. And the most surprising thing - with the recent price increases on X, many times O can be actually similar price or even cheaper, especially if you include all the extras.
Plus O has one of the best loyalty programs. After 10 cruises you get pre paid gratuities on all cruises, $250 on board credit and more.