well idk since i'm not from SA and i dont follow charts, but i do know brazil stans for the queen and its the most important music country there so i'll go with the queen.
Beyoncé, of course. Lady Gaga is only known among the South American gay community.
Yes, that's why even Do What U Want single release make it to my country Major National News, in which I can't remember a single moment Bey was mentioned (apart of Telephone).
In TVR
Duro de Domar
In the shows with higher ratings:
It's really hard on Argentina to be an non-Spanish speaking artist and have such a TV relevance. Gaga has made it.
The other countries are more similar to Argentina than Brazil. I.e., Peruvian icon Wendy Sulca admiring Gaga and singing BR
Even if i don't like her, i'm from South America and Beyonce is irrelevant here, i mean she has fans, but everybody knows Lady Gaga, while Beyonce only had 2 hits.
And Brazil isn't the only country in South America.