I'd usually play all kinds of characters to.. Mostly feline and canine now that I kinda think about it, but usually made-up species somewhat. Fantasy creatures, I don't rp with often, heh... but I do rp with them, take Pierce the crazy albino griffin, for example. Though semi-realistic and maybe unrealistic in a way characters to me are sort of their own species, and I might make them more often than you think...
Of course I do make realistic characters sometimes, but I might easily get bored. So on the poll I guess I just picked canine and feline, since those maybe the main source. Though I do have other kinds of species of characters too, so I guess it's just... random with me. I don't know! (I even have some human characters, too...)