After some thinking, I guess it must be these five:
1. Berlin Zoo
2. Prague Zoo
3. Cologne Zoo
4. Walsrode Weltvogelpark
5. Bronx Zoo
In no particular order. Deciding which one is my absolute favorite is honestly too difficult.
And yes, my list may give away that I have a soft spot for zoos with enormous collections, and that I haven't been to most of the really notable zoos yet (I haven't been to Berlin Tierpark, Zurich, Chester, Burgers, Pairi Daiza, Wroclaw etc. yet, not to mention that Bronx is the only zoo outside of Europe I've visited).
1. Berlin Zoo
2. Prague Zoo
3. Cologne Zoo
4. Walsrode Weltvogelpark
5. Bronx Zoo
In no particular order. Deciding which one is my absolute favorite is honestly too difficult.
And yes, my list may give away that I have a soft spot for zoos with enormous collections, and that I haven't been to most of the really notable zoos yet (I haven't been to Berlin Tierpark, Zurich, Chester, Burgers, Pairi Daiza, Wroclaw etc. yet, not to mention that Bronx is the only zoo outside of Europe I've visited).