We've done about 8 RCL cruises and 2 X (and about 10 CCL, 1 NCL, 2 Princess)
We've enjoyed mostly all of the RCL cruises. The first X cruise 5 years ago was awesome, on the Equinox. We just got back in May from a 10 day Italy/Med cruise on Reflection, it was pretty BAD! Food was not good at all, service was TERRIBLE! After 2 attempts in MDR, we gave up and stuck with the buffet! Pool 'action' was ok, sorta quiet if you like quiet and older music. If it wasn't for the bar service at the pool bar and the world class bar, this trip would've been a bust! Shows/nightlife was ok. Service by pool was great, same with outdoor burger place. The workers in the buffet were the bomb!
So, would we do X again? IDK, for now not really looking. We have a cruise booked in Oct on Navigator of the Seas, looking forward to it. Also, we did the Carnival Panorama last Oct., and it was awesome! The food, believe it or not, was better than on the Reflection! The service too!
Royal is next, it's been about 2 years, last one was on Symphony of the Seas, I'll keep you posted!
FYI: We're in our 50's. Saw people of all ages, I was surprised at how many younger ones were on our Med cruise! We were told it was going to be all old people, it wasn't. And hardly no kids! This applied to our first X cruise also. If you like nightlife, activities, shows, music, I'd stick to RCL or even NCL!