I've never really been too thrilled about Zoos. I went to the Reid Park Zoo a lot in Tucson as a kid and I have fond memories, but really I have never really been terribly impressed.
Well, my skepticism was laid to rest when we made the drive to Wildlife World.
The very first thing you'll notice as you enter the park is that it does NOT immediately stink of animal feces, unlike every other zoo I have ever been to ever. I get that smells are unavoidable, but I have never before entered a zoo unassaulted instantly by the unrelenting odor of beast poo.
Aside from that, a few of the habitats they have are very cleverly designed. A Jaguar habitat has a bridge over the walkway that the cats can sleep on so people can get very close looks and interactions with the animals. I've never experienced that before.
They had other attractions like that, such as giraffe feeding and a petting-pool of stingrays that were excellent up-close experiences with these magnificent creatures.
We got to see penguin and otter feedings that were fascinating as well. And the connected Dillon's BBQ restaurant didn't jack up their prices just because of their location (and the aquariums inside were amazing)
I highly recommend Wildlife World over the Phoenix Zoo if you are trying to pick one of the two.