Devils advocate....
The human might have molested his children
The human could bring more misery to more people
The human could have terminal cancer
The human could be a complete piece of shit. The dog could have been a service dog helping blind people function, sniffing bombs in Iraq etc
I'll give you the last one.
I don't know that there is "relatively little chance". There are a lot of awful human beings out there.
I agree that there's a counterpoint for everything I said, but statistically speaking, it doesn't make sense to put them on the table.
If you take a thousand humans there's going to be maybe 0.5% that are child molestors, 2% chance that he brings misery to more people, 2% chance of cancer, 5% chance he's a total piece of shit. So overall there's a 90%~ chance that the human is greater than the dog.
The dog has 0.0001% chance of being at all useful to anyone but you.
It would be absolutely selfish to choose the dog.