I would love to work with any kind of social caniform. Best would be African wild dog, but other good options would be dhole, Ethiopian wolf, gray/red/eastern wolf, most pinnipeds, giant otter, smooth-coated otter, or small-clawed otter. Outside of caniforms, maybe spotted hyenas. Just because I love how active, dynamic and interesting all these species are - in addition to the fact that many are highly endangered and receive less attention than, say, big cats or great apes, despite qualifying in my eyes as equally charismatic animals and often better keystone species, e.g. tigers can often survive in more degraded and less fully diverse forest ecosystems in Asia than dholes can.