I still really like La Cabrera, although I think its not as good as it used to be. But their bife is great, and they include a dozen or so free side dishes of things like beans and hardboiled quail eggs and potato salads and veggies.
Not cheap, and you need reservations.
Other places I have had very good bife-
Standard, over in Palermo Hollywood.
Sucre, on the edge of Belgrano.
1880- a great, classic, old style parilla on Defensa, at the far south end of San Telmo.
Parrilla Pena, a nice homey neighborhood place on Rodriguez Pena near Callao.