Burgers' has an obvious disadvantage here, given Singapore's location, but it is still a very strong contender. The Bush, more so than any other zoo exhibit I've seen, can actually be called a living habitat. It by all means is a tiny rainforest. Artificial, heavily managed and completely depended upon human care, but a rainforest nonetheless. It can thereby provide the free-ranging animals - reptiles, frogs, bats and almost 30 bird species - probably the very best enrichment a zoo can give, as they can interact with the plants, the soil, the water and each other. There are a few exhibits in there, which range from good (otter, turtles) to only adequate (aardvark, capibara), but the real star is the rainforest itself. There's even a tropical plant species (Dracaena bushii) decribed from Burgers' Bush and named after it!
But everyone seems to forget Burgers' has another tropical forest themed area. Burgers' had the wisdom of not trying to fit in any large mammals in the Bush (with the exception of manatees, which weren't even in the original plans and are now gone), so they opened the Rimba to house the larger species. The area - housing bears, banteng, tigers, gibbons, and pythons, among others - is a true crown pleaser and is loved by both zoo fanatics and the general public. While the rainforest feeling is certainly weaker, each and every exhibit in the Rima is a masterpiece.
Burgers' representation of the rainforest biome is, in Europe, probably only contested by the likes of Zurich and Leipzig. It is a triumph.
Yet, if any zoo can overthrow it, it would be Singapore. It has an immense advantage of being inside an actual tropical forest. But how does it use that advantage? Does it enhance the rainforest around it? Do they protect it or use it for its enclosures? The pictures in the gallery look pretty, but how good is it really?
No-one would argue Burgers' should win a match with a 'temperate forest' topic just because it is located in one. The same goes for Singapore's tropical forest. I can totally see Singapore win if it uses that advantage well, but I do want to hear a better argument than "it is surrounded by a rainforest therefore it wins".