Argentina or America for student exchange?

I think both are good options, I am from Argentina and I will try to help you, in Argentina, just Buenos Aires, the capital, a big city where is everything you need, also is the 2nd. safer city in the Americas, I guess schooling in Argentina is like in Australia, now in America, they're in summer vacation, Buenos Aires is so cold in winter, around 1�C | -3�C, but in summer is so warm, 30�C | 35�C, I think you should try with Argentina, a good place, with nice people and you will learn Spanish there, well, good luck with your exchange!