Use something that you are comfortable with and that fits the situation. You might just get an ear full. When you start talking to a total stranger you are developing a wee relationship with them. And listen very carefully. They re going to tell you everything that you need to know before you even ask.
Most people love to talk about themselves, but often have a tough time finding an audience.
Be a good audience when they start talking. Listen for clues to what they need, or what is missing in their lives. Ask the questions that will get them going. If someone says to me Not too bad. They will usually say, Yup, could be better.