Honestly, I can in all seriousness advise you to look at his short stories. Like Rudyard Kipling, King can write good novel-length work but he can get lost when given that much free rein. His short stories (as with Kipling) are often masterpieces that stay with you for years.

Outside of the kids books for my kids, I’ve probably stamped my Narnia passport 7+ times. More recently, Douglas Adams is still my favorite author, and Jim Butcher’s Dresden Files are very re-readable!

Consider picking up Richard Powers’s Bewilderment - he leans heavily on Flowers for Algernon, and unabashedly quotes it. Solid story.

For me it’s Sir Walter Scott’s The Lady of the Lake. Published in 1810; it’s a fun story, but more than that - his command of the language was breathtaking. When he describes the water flowing over rocks in a brook, you hear it.

Also notable for two (of several) songs that he wrote in this, that his characters sing. One is “the boat song” that the clansmen sing while rowing, about how great the Chief of their clan (Clan Alpine) is, which starts “Hail to the Chief who in triumph advances…” This became Hail to the Chief, which is played when the US President walks into a room. The other is a hymn that Ellen (the eponymous lady of the lake) sings as a prayer to the virgin mother, Mary - an ave to Maria. A few years after it was published, the book crossed the English Channel and this guy Schubert read it - and thought, hey, I could put that to music.

On top of all that, it’s got a twist ending that 200+ years later I DID NOT SEE COMING. Bastard had me hook, line, and sinker. Brilliant.

Anyway, it’s my favorite.