Golden Retrievers and labs have to be the ultimate great natured dog. When we first moved to the neighborhood, the golden across the street was the first one to "welcome" us!
She is always so happy to see me. There is also an Alaskan Malumate that lives in our neighborhood that is very friendly!
I would not advise just anyone getting a Jack Russell. I had one and they are very high strung and need a lot of room to roam or they get bored and then watch out! Mine chewed all the way through my dining room table leg!