I’m a vegan and an animal rights activist, and to me, animals are people, not property. In my opinion, the best thing we can do for non-human animals is to stop eating their bodies, milk, and eggs. Worldwide, we kill nearly 60 billion land animals and nearly a trillion sea animals annually for food. (Statistics on land animals are available here.) Stopping this slaughter would have a far greater impact than filing lawsuits over monkey selfies.
Some people have genuine financial or other obstacles to going vegan, and animal rights activists need to take human oppression into account in their messaging. But those of us who can be vegan can make a great impact on the lives of our fellow animals by refusing to exploit them, regardless of how photogenic or personable they are.