Yes, I have sailed on Carnival twice. But since then I have sailed five times on Royal.
Every person should pick what he or she likes. As for me, I am not going back on a Carnival cruise.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
Independence of the Seas 12/29/2013 Top-notch!