i'm leaning towards wolf or fox, even though that is cliche
it is a BIT difficult to figure out WHICH because i've already done art/done titles referencing him as "between reynard and ysengrin" - e.g. he used to be as darth vader ysengrin the wolf, fully invested in might-makes-right with the brute force of the empire behind him, but he is now reynard the fox, living by wit and cleverness first and foremost along with the rest of the rebel alliance...
of course the real dick answer to this would be to just blight some poor commissioner's inbox
"hey, i want one shitty au darth vader from my fanfic but as a furry please! oh, he's a krayt dragon."
"a *what*"
"yeah we see a skeleton of one in a new hope but otherwise the appearance is a bit all over the map in the comics and whatever haha, here's your money and good luck lol!"