Indeed!
I'm actually really surprised Ouwehands is last on so many lists. Maybe as
@Andrew Swales put it's down to aesthetics, and Gorilla Adventure has it's limitations there. The glare on the glass is horrible and the viewing is not particularly good, both indoors and outdoors. I get that, even though I'm personally not that easily put off by it.
I like the Ouwehands enclosure from an animal welfare perspective. The Netherland experiences a temperate climate, one in which weather that gorilla's don't like is rather frequent. While the enormous island of Apenheul is impressive, once the temperature goes down in winter the gorillas need to accept much lesser accomodation. But not in Ouwehands. With the large indoor enclosure, which includes live plants, deep mulch and tons of enrichment, the gorillas do very well here in winter. The outdoor enclosure also has it's advantages, as more than any other enclosure I have seen it stimulates the gorillas to climb, to use the impressive mulscles they're famous for. The cage construction also allows for extra climbing frames and very precise feeding from above, which lessens the chance that conflicts arise in the all-male bachelor group. Again filled with enrichment and deep substrate, along with corners to hide from both the public and each other alike, the outdoor enclosure is rather good from an animal welfare perspective. It could be bigger of course, but so could all gorilla enclosures.
Is this inherently better than Burgers's, Gaiazoo's or Apenheul's enclosure? Not really. But at least I think the enclosure should ge more recognition than it currently gets.