Value in Service

What is it people value? What draws people back to the same service provider? I realize this could be a list of many items. What would be interesting to know what is most important. Price; Expertise; Unique Service; Profressionalism; Trust; Post Service or there may be some important reason's I've missed. I would appreciate hearing back from people reading this blog. In your opinion what is most important thing when picking a service provider. Add any item you feel is missing. List them in order of importance.