Subway = Subte, Buenos Aires
It is the fastest and most practical way to travel throughout the city.
The token has a price of $0.70.
The very best way is by subte (metro) like the one in the picture. They´re quite similar of the rest of the world but without air conditioning.
Buenos Aires has an adequate subway system that gets you around portions of the city. It doesn't go anywhere close to the airport.
The Subte or Subway is a great way to get around the city for only .70 argentine cents but beware that it shuts down at around midnight.