Bunnies are the best because to kill one on the road is quite rare. Opossums are just plain greasy and while deer is the best, you need a tractor trailer to hit one and get it home before it spoils. Raccoon is also great roadkill, but you should backup and hit it again because in our experience if you go to retrieve it after just one wallop, it's not dead and they are quite unpleasant after being struck.