There are many people outside of the US so please state which country you are from and how popular the artist is in your country instead of just voting.
This topic has been debated many times, but who really takes the crown??????
Beatles
MJ
Elvis
Sales are a factor of popularity but sales can also be confined to one region.
MJ has the Guinness record for 1st artist(maybe solo??) to sell 100million albums outside the US. Another great example is Country artist. Many of them have higher sales than most of our favs but that doesnt make them popular worldwide because they sale the most in the US.