If you HAD to pick just one, I would pick the zoo. Both are full of hills, but I find the Wild Animal Parks hills to be far more steep and not necessarily well-paved. There were a few exhibits, such as the condors and tigers, that I skipped completely just because it was a hot day and I didn't have it in me to walk up those hills, and I am relatively young and fit. I'd imagine they would be difficult for someone in a wheelchair. Also, regular admission to the Wild Animal Park only includes one tram ride, so if the animals are sleeping or hiding during that tram ride, it's kind of your only opportunity to see them up close. I prefer the zoo where I can set my own pace and stop and really look at the exhibits that I like. The zoo also has a larger variety of animals. And, finally, the last benefit of the zoo over the WAP is that zoo parking is free, WAP parking is $9.00