For me nothing is as low as Zurich's orangutan cage, it is disgraceful and I suspect everyone voting for Zurich has voted on the zoo's reputation or just coz its Zurich so Zurich must win and the wonderful Masaola beats anything?! That orangutan cage is shocking, imo!! Read your comments on that photo thread again @lintworm you admit the orangutan prison is s..t!!
I don't think it's fair to attribute this result to bias (again). Facing most other competitors, Zurich would deserve to lose. I agree with @antonmuster that the apes should have been prioritised for development. And I agree with you that there's no defence for the current situation. But there's no defence for Wroclaw's monkey houses either. For larger species like the colobus, Wroclaw's exhibits are small, sterile, and lack privacy. I think they're just as substandard as anything at Zurich.
If Wroclaw's monkey houses neutralise Zurich's ape house, the competition comes down to what else is on offer. Both zoos have some outstanding and innovative primate exhibits. Wroclaw's barbary macaque enclosure, gibbon/rhino exhibit, and gibbon island are wonderful, and I love how outdated exhibits have been creatively expanded (e.g. capuchins and howlers). To my mind, though, Zurich's Masoala is the world's greatest (primate) exhibit; Semien unseats the Bronx as the world's best gelada/baboon exhibit; and squirrel monkey walk-throughs are always fun.
Zurich was lucky in its opponent, but it earns a win here.