I have never flown these four airlines to EZE, but this is what I know/have heard
1) AC flight to EZE has a stopover at SCL, adding four hours to travel time. Unless they are operating their seasonal direct flight from YYZ to EZE.
2) MX can have long layover in MEX, sometimes overnight.
3) I have friends that flew LAN to EZE, they enjoyed the experiences.
4) I have heard horrible experiences on Aerolíneas Argentinas as mentioned by Britenbsas. Also agree with avoid at all costs.