Both Coron and Siargao are beautiful and lots of places there to explore. It really depends on what you want to see and do. Both have direct flights to Manila so going to Manila is not a problem from both areas. If you love to surf and the beach, Siargao would be a perfect choice. But if you want to go diving, island hopping, and trekking, I would recommend Coron. So it is up to you to decide what you really want to do for three days.