I flew AR on the AEP-USH-AEP route (both legs MD80´s) and they were two of the most cramped flights I ever had. Seat pitch is really bad on AR and for a 3:15 hour flight each way it is quite a journey.
On the other hand, I flew LAN Argentina on the AEP-IGR-AEP route (both legs B732's) and seat pitch is much better with very good inflight service.