Who was the greatest monarch and why?

Determining the greatest monarch is subjective and often depends on the criteria used. However, many historians cite figures like Emperor Augustus of Rome for his role in establishing the Pax Romana, which brought stability and prosperity. Others might point to Queen Elizabeth I of England for her significant cultural and political achievements during the Elizabethan Era. Ultimately, the "greatest" monarch can vary based on their impact on their nation and the world, as well as their legacy.