Thanks to many helpful threads on this site, my wife and I just returned from two weeks in Argentina (10 days in Bs As, 4 days in Bariloche) filled with many incredible, incredible meals.
Our best steak-based meals in Buenos Aires, ranked and starting with the BEST, were:
1. Don Julio -- in our opinion, the best beef we had in Argentina. And so lovely sitting outside on the cobblestone streets of Palermo (our favorite neighborhood). Dinner for two -- with a delicious provoleta appetizer, two steaks (ojo de bife and chorizo), dessert, and a nice bottle of wine - ran us about $80 USD.
2. Cabana Las Lilas -- sure, it's touristy (like most of Puerto Madero), and it's real expensive, but it seemed like we got a lot of bang for our buck -- best bread selection we found! - and the service was pretty great. But definitely expensive. Giant lunch for two (salad, two steaks, dessert, wine) ran us about $130 USD. Beef was absolutely delicious (if not quite Don Julio delicious).
3. La Cabrera (original location in Palermo) -- our first parrilla experience. Such great atmosphere in there, and really, really tasty. We left ourselves in our waiter's hands and got a chorizo appetizer, two steaks, and an awesome dulce de leche dessert, and a bottle of Malbec -- all for about $100 USD. Definitely worth it.
4. Juana M -- based solely on the enthusiastic recommendation of a flight attendant I spoke to on the long flight to Argentina, we went to this lovely, relatively casual and cozy restaurant near Retiro. Dinner for two, with basically, the same dishes as La Cabrera, ran us about $60 USD. Best part about this place is the really ample, all-you-can-eat salad bar. And being surrounded by giant groups of locals having a great night out.
5. Fervor -- ended up here on our last night in Recoleta, and while it was quite expensive by local standards, we loved the scene. To me, it felt like a local trattoria in the Upper West Side or something. No tourists in sight, really.. just well to do Portenos out for a nice meal. Had some amazing lamb, steak, and surprisingly, some of the best dulce de leche ice cream of our whole trip. But, yeah, a splurge -- big dinner for two ran us about $150 USD.
PIZZA: Thanks to fellow Chowhounders, we happily gorged ourselves at Guerrin - the best pizza we tried.
EMPANADAS: our favorites were at Querido Gonzalez in Plaza Serrano, in Palermo. A fun place to grab a drink.
(But.. the best empanadas we had in Argentina were in Bariloche, at an AMAZING restaurant called La Salamandra Pulperia. Don't miss the potato dish either -- it was mindblowingly good.)
Finally, should add we had a great time at Tegui in Palermo, though it seems like Chowhound opinions on the place vary. It's definitely pricey for Bs As, but hey, it was our honeymoon.. and it was a really delicious, wonderful, romantic night.
Thanks everyone for all the good tips!