Michigan. Not only friendly, but not judgemental, very welcoming.
If you ask me what country, I say Scotland.
@uberbatman I agree with @jjmah NYers are friendly and helpful. Just a few month ago my girlfriend from MI was saying how incredible NYers were when she needed help or asked for directions. They were sure to give specific detail on what subway to take, which way to walk when exiting, cared about giving good info and being helpful, and they are very social. Back in the day of the pay phone, when I did not have change and someone could not break my dollar with exact change someone has more than once given me a quarter. My grandmother when she fell on the street, two people, strangers, helped her up into a shop on the corner. They waited with her until the ambulance came.