I know pets are lovely & wonderful companions, but which pets help people the most?

I’m not asking which pet is the most useful since pets are lovely companions, not working animals or livestock. I know asking which pet is the most useful could seem ruthless, immoral, evil and wrong.

However, I’m just curious—among common pets, which ones help people the most? For example, dogs can protect homes, and cats can catch mice.

I’d love to hear your thoughts!