"As a dog owner I've found that in many respects dogs behave better than humans."

I'm calling bullshit. Your expectations are completely different. In terms of harm alone, dogs simply don't have the capacity to commit the many evils we associate with humanity. Lack of such capacity should never be mistaken for goodness.

Dogs have a very limited cerebrum compared to a human's. This causes a dog's choices to be relatively more influenced by emotion and instinct than thought. Humans, with their destructive capacity, would be terrible making decisions the same way. For example, it would be immoral to shoot someone you don't know just because he's approaching someone you trust and you get bad vibes from him, but we expect a dog to bite in such a situation.

It is also this raw, mammalian emotion that can make pets so endearing. Dogs (and cats) do have the capacity to experience and express fear, trust, loyalty, and companionship. To get the same from a human, one must first gain the trust to bypass the inhibitions and misdirections created by a sophisticated human cerebrum. Developing such trust to share emotions with a human is more demanding and less reliable, but I don't think a pet can ever offer the richness of a human relationship.

(Of course, unlike Robin, I don't have a PhD in psychology. If I'm off-base anywhere, I'd appreciate a nudge in the right direction.)