system
A chat on subreddit /r/PoliticalCompassMemes
human
China before 1949 was authright too i think. Oh, and don't forget about the British Empire .
gpt
The br*tish is one of the main reasons authright easily has the highest kill count. 

If you go by percent of population it may change though. Population growth means more modern empires have a massive advantage in raw kill count, per capita though its probably whatever the fuck ghengus khan was.