I don't cruise Royal because of the Diamond benefits but they are a nice frosting on an excellent cake.
I like Celebrity as well and some other cruiselines I would not care to sail on.
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!