I'd probably save the human if it was just a regular person. I just think others are less likely to be negatively affected by the situation. When my friend's dog died at the age of 14 (she'd had him since she was 6) she mourned pretty badly. At that point that dog was the only creature who really loved her in the world. Yet, despite that, when her ***** of a mother died, it hit her harder, despite the woman not deserving an ounce of her love. I just think humans, IN GENERAL, don't innately place as much value on animal's lives as the lives of those who are close to them. I bring that up to account for my family members who are also close to my dog. What's more, my family members would also be saddled with the guilt of knowing that another person had to die for the sake of our dog. If the dog died the guilt would likely be less so for the other family, since a random dog vs random human will almost always end with the human being deemed more valuable.
Now if the person did die, that person is most likely close to someone, thus more pain will probably result from their death. Comparatively, I know I can live with my dog dying, as sad as it would make me. The dog doesn't give a fuck. It's dead. Yes it will experience a moment of fear in its death, but so will many other creatures (human or animal), and at least a dog can't fully understand what death means. Hell, it might not even fully understand "I'm about to hit the ground super hard and explode everywhere". The most I'm getting out of this is the hope that my dog might experience a more peaceful death later in life and saving myself some sadness, which just doesn't seem worth all the pain the death of another could cause after they're already dead.
Aside from that, the cognitive and complex emotional capabilities of dogs make me value them somewhat less. I mean, on a base level, not accounting for any other traits or factors, I consider more intelligent people to be of more value than less intelligent people, so why would that value change across species? Of course, other factors (like selflessness), play a big role too. So if that super smart person happens to also be a psychopathic asshole, then I'd probably opt to save the dog. However, since I can't know that, I have to go by what I can extrapolate from the situation, and I think it's generally safe to assume human brain > dog brain.
I don't buy the whole "my responsibility to take care of the dog" thing. Responsibility, at its core, is utterly subjective and self-appointed (repercussions are merely an attempt to force one to adhere to a specific set of actions, not actually forcing responsibility upon them). I will gladly disregard my "responsibility" if I feel there is a more important matter to attend to at the moment.
