I wouldn't say any of our neighbours are our "friends" because we don't mix socially. But we get on extremely well and we buy birthday presents for our neighbours' two children and exchange Christmas cards - and they buy us a small food hamper. Our neighbours on the other side are also very nice but their social lives revolve round the church and, as non-believers ourselves, we don't have much in common. But the wife occasionally bakes bread, scones or rolls and brings some round to us - which is really nice of her.
I had a very dear neighbour who lived a few doors away from us. He was an elderly widower and used to come round to have a cup of tea and a chat. I was sorry when he moved to be near his daughter but we kept in touch by phone and letter. Sadly, he died a few years after moving.
When we were first married and lived in rented hospital accommodation, our neighbours were also people that my husband worked with and it was a very communal atmosphere. We are still friendly with one family after nearly forty years.
We've only had one set of neighbours that we really didn't get on with, when we lived in Horsham, so I suppose we've been quite lucky.