There are many questions in my opinion. However for some people, all they can handle is one question and often they choose a very broad philosophical question, such as "what is the meaning of life?". Or questions which they deem to have a "religious" nature.
However in my opinion, the big philosophical questions are the ones that you find worthy of your mental and intellectual time. For me, there are broader questions, such as the one I mentioned above, as well as the origin of life, the existence of human life (both in small societies and the entire world co-existing), common religious questions, and how the world as we know it will come to an end.
I also have more specific philosophical questions, such as how does my existence relate to anyone else's (metaphysically speaking), how is my existence more, less, or equal in importance to the existence of high ranking social figures, etc etc.