The first horror story I ever read -- perhaps the first story of any type, not counting comic books -- was a short story titled THE TELL-TALE HEART. It was written by a little known writer named Edgar Allan Poe.
This may seem blasphemous to some, but when it comes to short stories of the horror genre Edgar Allan Poe is king (pun intended).
If Mr. Poe would have lived in our lifetime, and past the age of forty, would he have enjoyed the huge success that Stephen King has had, and is still having? It's hard to say. In his lifetime he had only one published novel. He was known mostly for his short stories. Some writers can't make a successful transfer from short story writer to novel writer and vice versa.
It's probably impossible to make a completely fair comparison. It's sort of like comparing a baseball player from decades ago to one of present day. You just can't account for all the variables.
To conclude I sometimes like to go back and read something from Mr. Poe that I have read a few times before. For now, however, I am about to read DOCTOR SLEEP from Stephen King.