In case you do not choose your cruise by destination, ship, company or price, Cruise Critic have produced a table comparing the loyalty benefits you can acquire from sailing with different companies.

Here is the link: http://www.cruisecritic.com/blog/index.php/2013/08/19/cruise-line-loyalty-with-chart-break-down/

If you would like more detailed information, please visit their article which takes an in-depth look at what each loyalty scheme offers.

http://www.cruisecritic.com/articles.cfm?ID=73