One possibility would be to allow a section of a country to secede if 60% of the population votes to do so. That might eliminate a popular reason for war in some situations.
The (forbidden) answer has been staring everyone in the face for half a century: bring back colonialism.
http://unqualified-reservations.blogspot.com/2009/08/from-cr...
How would you find out? In failed states I would think the mechanisms to solicit opinion don't exist to begin with.
This boils down to a long term vs short term question. State building might save a huge number of kids 5 years from now but no kids now unlike giving food.
The problem with a ranking is that it suggests a sequence of actions, when in reality you want to do more than one thing at a time (state building and giving food).