Thanks for your replies. Of the two options, which one would you recommend? The 85 minutes intra EZE connection or the 3.5hr AEP-EZE connection?
I have a big duffle and a back pack. I don't expect to check these in for United, but US airlines are more lenient with larger carry ons.
Aerolineas Argentine may require me to check on the USH-EZE leg.