Best place to buy Brazilian reals

Does anyone have any suggestions where to get the best rate when buying Brazilian reals? Cuevas? Bank? Instant teller in Brazil? Use dollars or pesos to exchange?
I have never been to Brazil but in my experience traveling I alway get money at the airport using ATM. Don't know if that works on an AR peso account.
I travel to Brazil about once a month. Brazil is a 100% credit card/debit card economy. You can use your card almost every place - restaurants, cheap restaurants, fast food,hole-in-the-wall kiosks, cheap cafe shops, taxis etc. I have even used cards in small villages in the amazon.

Having said that, there are ATM machines every where , which discharge up to 2000 reals in one shot...almost 500 usd. Of course the machine will charge you something, as will the bank.

I have not come across many cuevas in Brazil. Whenever I want Reals, I take it out from ATM. I have never been inside a bank in Brazil ( other than the ATM area).

Once you arrive at the airport, you can use the ATM machine there.

Or you can take a pre-paid taxi - using yr debit or credit card - ( all Brazil airports have pre-paid taxi) and go to your hotel and look for a machine nearby. I did not find any difference in machines at the airports or elsewhere. Personally, I avoid using at airports - as there are 100's of stories of debit cards being duplicated in Brazil after being used at a ATM in Brazil. So I prefer to use a ATM machine at some high-end hotel where I envisage, higher security preventing tampering of machine.

Hope this helps.