Zoo Tycoon 2 and Wildlife park 2 are both my favourite genres of games. I love simulation games and sandbox games such as these and I have created so much parks it is unbelievable, but especially on Zoo Tycoon xD I love the creative aspect on ZT2, but also love the realistic-ness and the accuracy on Wildlife park 2 because it focuses on not just the animal's satisfaction, but the plants.
In my opinion, I prefer ZT2 because it gives you more freedom building your park whereas Wildlife park 2 has more of ready-made buildings and not many variety of decorations and animals you can use for your park.
I would love to hear what you guys prefer!