That was kinda my train of thought, and I agree with your conclusion. Although Antwerp may have contributed more to the okapi breeding program, Zurich has conttibuted 1.2 million to Lewa conservation in Kenya and Masoala in Madagascar.
I also voted 2-1 Zurich, though my judgement on Zurich mainly comes from the zoochat gallery and @lintworm's reply here. Antwerp has a tendency to retain certain large mammals such as elephants, giraffes, hippos (and maybe rhinos in the future!) despite having not enough space to house all of them. Compare that to Zurich's elephant enclosure and see why I think Zurich should win. But Antwerp should receive credit where it is due. I really enjoyed the Philippine Mouse Deer (a species that eluded me until my visit to Antwerp) and their enclosure was about as good as they get in nocturnal houses. Their animal houses are as charming as they get, sometimes on par with those in Berlin, but they just shouldn't squeeze so many large animals into them. One of Antwerp's most iconic species is an ungulate, the okapi, and Antwerp has been highly succesfull with this species. For these reasons Antwerp surely should receive at least one point.
Reading the arguments and evaluating again the strong conservation role Zurich have, I am switching my vote to 2:1 for Zurich. Personally don't think, that Lewa savanna should be considered in this competition, but The Lewa conservancy partnership, definitely counts .
It would help if you could verify whether the information you post is actually correct, that would save quite some discussion. The 1.2 million USD was the contribution a few years ago to nature conservation for a whole year for a total of 10 projects. In 2018 this annual contribution was even higher at 1.8 million USD according to the latest annual report. Since 1998 Zurich has donated roughly 1.7 million USD to Lewa conservancy and 700.000 USD to Elephant conservation in Kaeng Krachan since 2009. I was not able to find specific contributions for the past year for either project. These are their only conservation projects where ungulates/elephants benefit, but for what it is worth Zurich has donated close to 5 million USD to protecting the Masoala NP in Madagascar in the past 25 years...
