The most notable theocracies - Iran and Saudi Arabia, do fairly well compared to the other two forms of government. I wonder why they're do better than one might expect.
Saudi Arabia is not a theocracy, it's a regular old monarchist dictatorship with some window dressing, and on pretty much any measure they do worse than their capitalist competitors like the UAE or Qatar.
Iran, Afghanistan and the Vatican are the only modern theocracies.