I went to Australian National Zoo at Canberra and I love it, there is tasmanian, koala, kangaroos of course dingo, liger and tigon Plus Dallas Zoo and Forth Worth Zoo are world class zoo twenty minutes away from here
Among those I've seen: Detroit, Cincinnati, Cleveland, Toronto, Bronx, Lincoln Park, Brookfield, St. Lous, San Diego, Los Angeles, Phoenix, Washington, D.C.; Seattle; Miami; Philadelphia; Pittsburgh; London; Edinburgh, Tel Aviv; Jerusalem...i've seen a lot of zoos.
In the US, of the ones I've seen the Bronx and San Diego obviously stand out but two other truly fine zoos, well worth a visit if at all possible, are Cincinnati and St. Louis.
I got to visit the Washington DC Zoo at the Smithsonian in Maryland about two weeks ago. It was awesome. They provide a lovely habitat for their tenants, and since it was in the middle of autumn, it was simply gorgeous.