I would still bring cash to Buenos Aires.
I get my ATM fees reimbursed by Schwab so from the ATMs I am getting 17.20 ARS to the USD. If I did not get my ATM fees reimbursed it would be 15.83. ATM fees are extremely high. From the cambio yesterday, I received 17.80.
ATM Fees 196 AR$ (about US$10)
It's ridiculous, banks now charge AR$196 , about US$10 ATM fees with a limit of AR$3,000 withdraw. It happened to me at HSBC, maybe there are other banks with other fees? I will report if I find out. But it looks like cash or credit card are the best options.