The opening chapter suggests that Ralph is clearly the best boy to lead the group. He is physically superior to most of the other boys, seems able to win their confidence, and seems to genuinely iterested in helping the stranded boys best deal with their situation. Keeping reading to see how this works out :)
In chapter one, Ralph is obviously a good leader. He is sensible and physically capable. He is, however, a bit niave. He sees the island almost as a playground and says that his father will come to rescue them.