Ask HN: What's the best way to pay your customers?

I am currently working on a website where there will be a monthly competition and the winners will need to be paid. I am open to considering both cash payments as well as cryptocurrency. My customers may be based all over the world. A simple Google search did not turn up much useful information in the first 5 pages of search results.

Can the community recommend any service I can use to do this? Ideally the service would also take care of any tax implications if required by law.