I've cruised both lines and like both for different reasons. I would sail on either line, given the chance. Carnival has larger rooms and I think their food is better, not that we didn't have plenty of good food to eat on Royal Carribean. Royal Carribean has a more "upscale" feel, and I think their service is better and their entertainment is slightly better. My last three cruises were on Carnival and my upcoming one is on Royal Carribean. When comparing the two lines for our upcoming cruise Royal Carribean had a better price (about $50 per person), free upgrade to an ocean view cabin and an extra port (we like port intensive cruises).