It seems dictatorships work better (actually I can't think of an example off hand) AND wildly worse. Dictatorships compared to republic is like male compared to female: the main difference is just a much wider spread. So you wind up rolling a much bigger set of dice with dictatorships and then survivorship bias and human bias towards picking off the high spots makes the result look good.

Further, would a dicatatorship work well for long in the absence of republics from which it could steal ideas? I don't think there is a dicatatorship with a good record of innovation and technological development. (Hitler's Germany SPENT technical capital it had accumulated before, Hitler didn't last long enough to see if Germany would have been the exception).

North Korea, ceteris paribus, does not seem to have been helped by dictatorship.