Short version: This is a beautiful place with attentive hosts. Pick it and don't look back.
Long version: Sometimes you have a great apartment with OK hosts, or you may have helpful hosts with an OK place. But Eugenia and Santiago may be the best hosts I've had in BA so far. They were quick to respond to my questions, and even fulfill a maintenance request. And the interior design of the apartment is wonderful: from the art to the many little touches like tea, snacks in the fridge, scented candles... it feels like a hotel. I miss it already. This is a great place with great hosts. They put a lot of work to make it shine, and it shows.
To touch it all off, there's a lovely bakery/cafe on the ground floor of the building. Wonderful place. I miss it already.