If the EU was defined as a country, I would say the EU.
But since it is not, I would think it d be the UK. Why?
quite obvious: it s the only nation in history that has managed to almost conquer the whole world and still lives to profit from it. Its legacy is still here and everywhere on this planet: language, conflicts (Greece - Turkey - cyprus, Israel - arabs, India - Pakistan. The british often ruled by dividing the people they conquered, they used them against each other, fe in cyprus the military police existed solely out of Turkish cypriots ), still military/politically/economically dominant (NATO, Commonwealth Nations), Spread of religion (protestantism), ...
no problem, the moderators haven't adressed me on this yet so I assumed it was ok. I m probably going to change it anyway , I m not used to changing the format so it may take a while for the new one