La Cabrera is very good, but depending on your bubget you can get good steak almost anywhere in BsAs.
One of my favourites is Aporto on Scalabrini Ortiz, although it does not have the ambiance.
This all depends on what you want, romantic setting, or the best food. Personally I always seek out the places that the locals eat at. you pay less and the quality is always good.
Finally if you go to La Cabrera try to be early or book in advance, as it is very popular, ie busy.
Suerte Bob