I'd go with G3 (Gol). AR is, at best, unreliable.

Have you also considered TAM which also has a flight GIG-EZE that arrives @13:10.

If you were to fly into AEP, 3 hours is sufficient time (especially on a Sunday evening) to transit between airports.

Since it appears you're Australian, have you flown into Argentina recently, or would you have to pay the reciprocity fee if you transited via AEP? The fee is currently US$100 good for multiple entries for one year.