The exhibits that you mention here are no doubt good, but the best in the world?
I would even say that the exhibit for snowleopards is not the best in Sweden. Having seen the one in Nordens Ark, I would say that it is better (not that Kolmården's is bad).
About the savannah, there are many more savannahs in the world. And the savannahs in warmer climates, such as San Diego, simply looks more naturalistic.
Well, I live in Denmark, so I know that. I am just saying that the savannah in Kolmården is indeed very good, but can hardly be considered the "best in the world".