There is NO question that Temaiken is a far far superior place. A veterinarian I know, former employee of the Palermo Zoo, told me that Temaiken is the only zoo in Argentina that belongs to an American zoological association that is considered the standard bearer of the world. He said that conditions at the Palermo Zoo are poor but I knew that just by looking. The architecure of the original buildings is very interesting but as a zoo experience it is grim.
You can take an express bus to Temaiken from Plaza Italia. Temaiken is really a very impresive place. One of the best places in the whole country.