I went through this process when planning our first trip to Africa and once we decided on Namibia as our destination, I then looked into an animal specific to Namibia. One that probably isn't found anywhere else, unless it was a relocation animal to a private ranch. That meant it was the Hartmann's Mt Zebra, home range Namibia.
While Namibia is known for it's large amount of Oryx, the Oryx can be found in many countries in Africa in hunt able numbers.
Other countries/animals for me:
Cape Mt Zebra, South Africa
Crawshay's Zebra, Zambia
Kudu, Botswana
and I'll probably be a rest home by the time I get those three hunts done.....