Rulers who conquer tend not to be wise or virtuous, because if they were they wouldn’t conquer. I can’t think of an example of a benevolent autocratic ruler that outperformed the average democracy when it came to the well-being of all their subjects (including the conquered). Some rulers can use the spoils of war to bless some of their subjects, but that just shifts wealth around and causes incredible misery for the deprived.

Productivity requires decentralized decision-making. The more centralized the power structure is, the lower the overall productivity of the subject population.