Greatest Empires

You are going to be the teachers for this lesson, your lesson must be no less than ten minutes long.  Throughout history numerous groups of people have attempted to take over the world and gain the most amount of territory.  Though each group is worth mentioning the class will only look at the top ten: Ottoman Empire, British Empire, Mughal Empire, Mongol Empire, Russian Empire, Qing Dynasty, Umayyad Caliphate, Roman Empire, Achaemenid Empire, and Akkadian Empire.  

Who's empire do you think is the greatest?  Why? (It does not have to be one from above)