I'll give a quick overview of the bird exhibits at Antwerp:
Let's start with something less-than-ideal, the Flamingo pond. Housing American flamingos, this pond is viewable from the Flamingo Plaza without entering the zoo. Even though, IMO, it's a beautiful piece of zoo architecture (unobstructed views from the restaurant), keeping flamingoes clipped isn't perfect husbandry.
As you enter the zoo, there's the Penguin Rotunda. Stars of this exhibit are the African penguins, which have an enclosure that's as good as any. Far more interesting, to me at least, is the aviary attached to it, which houses a variety of European birds (hoopoes, European turtle doves, ruffs, pied avocets, ...)
In the indoor enclosure of the Valley of the Great Apes, there are three smaller all-indoor enclosures, one of which houses (last time I went this one was being refurbished though) black-faced lovebirds and Madagascar partridges.
Then Antwerp's crown jewel, the Buffalo Aviary. This magnificent aviary houses a large variety of African birds such as hooded vultures, Rüppell's vultures, lilac-breasted rollers, fulvous whistling-ducks, guineafowl, yellow-necked francolin, violet turaco, laughing doves, Abdim's storks, ... This aviary is one of my favourite zoo exhibits of all time.
As we follow the path, we arrive at Freeze Land, which houses three species of penguins: King penguin, macaroni penguin, and gentoo penguins. This exhibit isn't great in my opinion, but not too bad either. Notable is also that Antwerp breeds its king penguins semi-regularly, with a chick born almost yearly.
Next is the Reptile Building, which has a greenhouse with Gouldian finches and red fodies. While not the most exciting of species, I do really like this part of the zoo because of the combination of active birds with the more passive iguanas and tortoises. However, it's not great to visit when it's busy, since the small path gets packed pretty easily.
The Wetlands Aviary is a large, high aviary housing another group (pair?) of Rüppell's vultures, marabou storks, northern bald ibises, and black crowned cranes.
Finally, the Bird House houses the majority of Antwerps birds. There's 4 "zones" in this house: first the indoors, then the dark hallway, small outdoor aviaries, large outdoor aviaries. The indoor enclosures are quite spacious for their inhabitants, and are well-furnished. Highlights are green aracaris, barred buttonquails, chestnut-bellied sandgrouse, red-flanked lorikeet, and Goldie's lorikeet.
The dark hallway houses almost (?) exclusively estrildids, without barrier between visitor and bird, although the birds don't always realize they should stay in their enclosures. Not the most successful way of exhibiting birds, but Antwerp pioneered this method and it looks pretty good.
The smaller outdoor aviaries are big enough for their inhabitants, mostly Asian or African passerines combined with pheasants. IIRC these aviaries have no real rarities, but it's still quite a nice line-up with Sumatran laughingthrush, blue-faced honeyeater, red-and-yellow barbet, and Palawan peacock-pheasant among others.
The three larger outdoor aviaries are themed geographically: the first one has southern European species (European thick-knee, European bee-eater, rosy starling, ...). The second has African species (Vieillot's black weaver, village weaver, green woodhoopoe, African olive pigeon), and the third houses a trio of American species: northern cardinal, crested oropendola, and (nominate ssp) grey-winged trumpeter.
As mentioned before, Antwerp is currently emptying its bird cages on the station-side, which is unequivocally a good thing, although I am sad to see all these birds go.
However Antwerp is also getting new bird stuff, as sometime in the future, Antwerp will have their old Bird-of-Prey Aviaries used again, this time as Parrot Aviaries. This wil finally give a good spot to their military macaws (among others), of which they are studbook keepers.