Hmm. assuming I were serious, let me explain why i choose boxer, and why the others are not so great
Comedian - Sure i might need a laugh for my sanity, but seriously, what's a comedian gonna do against a Hound? Call it malnutritioned?
Photographer - Pretty much useless majority of the levels, since Wi-Fi is somewhat uncommon. Plus, what's the point? Research?
Librarian - Considering their from the Frontrooms, this is also useless, they'll be as confused in the Backrooms as I would.
Priest - I doubt they can help my sanity with a prayer. And holy water, really? You can't get that from the Frontrooms, at least from what I know, and that also won't help me either.
Zookeeper - Sure they might be familiar with animals from the Frontrooms, but they can't go against an entity
And finally, a boxer would be VERY helpful for these reasons
Which is basically what you need to survive besides necessities.