I generally leave before the peak of the evening departures, and fly in a premium cabin, so while I don't have any check-in wait to speak of, I've had trips where either the security line or the passport control line took an excessive (and unexpected) amount of time. I usually get there about 2.5 hours before flight time, because I allow for traffic, which I usually don't get (being on the closer-to-EZE side of town, right near the highway onramp, and just before peak traffic).

Remember, if you miss your flight, you might not get home for at least another day.

Besides, the early arrival allows me to play WLIW.*

*Which Lounge Is Worst