I do not think one of the three Utilitarian theories is strong enough to be fully defensible; however if I were to choose one it would be the Objective List Theory.  This theory strives to increase things that will foster knowledge and relationships; things imperative for modern human civilization.  We have always been social creatures but over time we have become the only animal to ever live in such close proximity to each other or work with each other so comprehensively.    To foster relationships with others and achievements in the contemporary world means to be generally successful and happy as a result.  I think that the Objective List Theory is the most applicable to today’s society however I also think that the Mental State Theory has its merits.  This theory instead strives to foster internal wellbeing and mental solidarity.  I believe that it is important to further personal growth almost more than relationships.  I think to combine the two theories would be the best of all worlds because you would have a focus on personal development but also on furthering things around you that will increase your overall wellbeing in an environmental and social aspect.