Having seen only a few on this list and being in the U.S., Bronx and CPZ doesn't do much for me. Roger Williams is ok, not the greatest. Short, bowl-shaped and shotcrete. Doesn't jive well. Woodland Park Zoo, is a slope. Reminds me of Cincy's horrible excuse for an exhibit, just with more greenery. Stone Zoo does it for me. They basically meshed in a section of the mountain. The cats can be at visitor level or at the top of the cliff. The leopards are surrounded by Markhor and stalk them within the confines of their exhibit. Visitors wait and search for the cats but they blend in well with the natural rocks. It is always nice to look up and find the leopards 45' above you, set back. The female uses the mesh to climb on one side while the male bounds the rocks as if they were a staircase. It looks great in any season, but was really nice this year with all the snow.