Having visited both collections last year this could be indeed a very close call.
Does
@TeaLovingDave have a good eye on the collection in Wroclaw's reptile house in terms of this theme? The vast majority there will live in the tropics, but therefore not all in the (rain)forest.
The collection is very large in Wroclaw but, on the other hand, the terrariums in Tierpark's Alfred Brehmhaus are of very high quality, while the enclosures for tropical cats and bears, in themselves not that good (nor large), also seem to me slightly better than the ones in Wroclaw.
Tierpark's best lemur enclosure probably has more of a Mediterranean feel than tropical, but that's just my impression.
Wroclaw has a beautifully restored birdhouse with an unsurpassed collection, while tropical birds are not a stronghold for the Tierpark.
Large parts of Wroclaw's Afrykarium are not dedicated to tropical forest, while the ABH is exclusively dedicated to the forests of Southeast Asia.
For mammals: both have Balabac chevrotain, Sumatran tiger, Crested black macaque, NG Short-beaked echidna and okapi.
Tierpark has Aye-aye, Bawean deer, Asian golden cat, Bear cuscus, Guinean bearded Saki, Belanger's tree shrew, Venezuelan Red howler monkey, Sulawesi babirusa, Roloway guenon, White-bearded Palm Civet, Coquerel's sifaka, among others
Wroclaw has Black howler monkey, Diana and L'hoest guenon, Eastern Putty-nosed monkey, Eastern bongo, Goodman's mouse lemur, Golden-headed lion tamarin, Hammerhead bat, Indochinese clouded leopard, Sumatran Prevost's squirrel, Sri Lanka Rusty-spotted cat, Visayan spotted deer, Western pygmy hippo among others.
Quite close I think
At the moment, I would cautiously give 3-2 in Berlin's favour, as the enclosures there are newer and better, but I look forward with interest to others' analysis and I do not rule out the possibility that the (size of the) reptile collection in Wroclaw will ultimately be the decisive factor.