Our departures and arrivals waiting times at EZE over the last few years have always been acceptable and have certainly improved compared to years gone by. We used to order the taxi for one after after scheduled arrival time now we make it half an hour. Immigration is certainly no worse than many major International airports I've been through.
Security can be either empty or packed which it was the last time we were there. However it was very fast moving and took no longer than twenty minutes.....probably the longest I've ever had to wait. Should say although I've arrived at so called busy times I've never departed in the evening when it's at its busiest.