What is the best city in Brazil to learn Portuguese in?

I believe southern Brazil’s accents and pronunciations are easiest for an American to learn.  I learned in Minas Gerais and didn’t understand the difference until I went to Sao Paulo for short visit.  While in Sao Paulo it was much easier to pronounce the Portuguese words.  The “R’s” are a good example.  In Sao Paolo the “R’s” are like an American sounding “R”.  In Minas Gerais an “R” sound like “ear-He”.