I've found it works best to match animals to personality more so than anything else. All animals have certain behavioral characteristics that vary from species to species, but generally hold true of most individuals within a species. To use myself as an example, badgers tend to be home-bodies and while they're tolerant of other species in their home range, they generally prefer to be left alone. Not aggressive, they are never-the-less ferociously protective of their families and friends (to put it in human terms) and won't hesitate to fight off anything that threatens them, no matter what it is. They're quite fussy about their hygiene and like to keep their setts meticulously clean. All these fit my own personality quite well, and also fit the personality of the character I wanted to portray here. So, yeah. Knowing yourself is the most important part of choosing a sona I'd say. :p. Good luck.