I think democracy has proved itself superior in many ways to all other forms of government. This can be seen both in their longevity (few, if any, stable democracies have stopped being democracies), and in comparative studies of popular well-being.

A key asset for the democratic state is also that people, even though many are indifferent, have far greater reasons to take politics seriously and figure out how stuff works. This is important both because people then educate themselves (and knowledge is the solution to many ailments inflicting nations) and because they have take other people's interest seriously - you cannot convince people to vote for you and support your politics unless they see it as being in line with their interest.

The importance of knowledge and thinking beyond your own narrow interests should not be underestimated, and democracies have these features built into their very framework in a way that other governance systems don't.