I believe Ralph is better fit than any of the other boys to be the leader.
One reason is because he has rules that keep everyone in check (kind of.) "We can use this to call the others. Have a meeting. They'll come when they hear us-"
Another reason is because Ralph has the conch that gives people the right to speak. "That's what this shell's called. I'll give the conch to the next person to speak. He can hold it then hes speaking."
Another reason is because Ralph has the idea of the fire for the ships to see and rescue them. "There's another thing, We can help them find us. If a ship comes near the island they may not notice us. So we must make smoke on top of the mountain. We must make a fire."
Some people may think Jack is a better leader because he's all about hunting pigs, but he is losing his humanity, all he cares about is pigs.
In conclusion, Ralph should be the leader because he's smart, on his toes, and gets everyone doing what they need to do.