As others have pointed out, this question can be answered in many different ways. Perhaps before diving into the endless possibilities, it's worth asking yourself a few questions:
a) Why do I want to make money online? Is it because the more conventional methods of making money are not open to you, or are you perhaps thinking this is going to be easier? (It's not an easy way to make money, by the way.)
b) What am I enthused by? If you still want to make money online, then the best way to stick at something that is going to suck out your energy is to do something you enjoy. What interests you? What are you knowledgeable about?
c) Where can I find buyers for whatever I have to offer? In other words, do I know where there's a market? The answer may be linked to the previous question. For example, if you're a gamer and a member of a gaming community, then you will know how to access that community. They could become your first customers.
Taking this approach will be a more fruitful way forward than making random choices which are less likely to succeed. Happy to talk this over if you wish.