Good question. I think maybe there are different levels of neighbor. Some keep to themselves, others are more outgoing. For me, it’s someone who stops to say hi and chat, someone who exerts a bit of effort to maintain their property, who respects boundary lines but isn’t necessarily a stickler about it.
A good neighbor lets you borrow a tool if the need exists. They have a sense of decorum when it comes to making noise, they keep an eye on the place when you’re away, pick up the mail, etc..
In general, someone who’s cordial and considerate.
3 Cents' 