I have everything Stephen King has written. My favourite is Insomnia, closely followed by The Stand, which is one of the best books I have ever read. Carrie and The Shining were the ones to give me nightmares (both overdue for a re-read). The Dark Tower series is, for me, the failure. Went on for too long and a very poor ending.
If you want to start with a "classic" Stephen King then Needful Things or The Tommyknockers are good ones - not too long but have the unmistakeable King touch