Currently only the totem shapes are available for your animal companion as a totem ranger.
Currently the best option is Bear, by a wide margin, but since seeing everyone running around with a bear because the other animals are so far behind would be boring, currently you can make them look like any of the Totem options. But only those. I appreciate that we have these options.
It would be good if you could make them look like any of the list of animals.
The concept is the same. But it would be good if you could have an animal companion such as a Direwolf, and have it not be awful, considering it is a base option. As opposed to having to pick Wolf totem instead (and picking a Bear).
If you're worried about verisimilitude right now I can pit my Parrot Animal Companion and have my Parrot beat the snot out of a Direwolf because that person picked an awful choice. If they want to be in line they have to take the poor Direwolf behind the shed, RP putting old yeller down never to return and trade it for a Wolf, that will be somehow stronger in each and every way.
Alternatively, I would suggest making Animal Companions have the Bear statline, so all animals remain just as useful without having to disguise them as something they're not for it.