It depends if you want to carry around a lot of cash with you.
I usually take Dollars or Euros to whichever country I am going to and plan enough for the first few days. After that, I use the ATM but do it in bulk rather than going every day.
This saves the need to carry vast sums of money that you have changed ahead of time (and may need to change back if you don't spend it all). Most places have ATMs now. about 4 years ago