The US is the most imperial evil empire that has ever existed. Biggest exploitation, largest number of bases in largest number of countries, non-stop influence both hard and soft, immediate hostile reaction to *any* serious disobedience. The collected death toll of American global ambition outshines any other single conflict
Okay, to be fair, total American imperialism death toll might come 2nd or 3rd, after the Mongol conquests or the Taiping rebellion. These things are often tricky to count :v