Not currently reading, but I saw this in a list of "most popular" books.
Top of the list was "Flowers for Algernon" by Daniel Keyes.
I first read this while I was a teenager, recovering from an appendectomy. Those three weeks were magic, as I read "All you Zombies", "I have no mouth and I must scream", "A Rose for Ecclesiastes", and the original short story version of "Flowers".
Talk about being hit over the head with stories that just seared themselves into my teenage brain.
Later I read the full book version of "Flowers", and watched the film. Neither compared to the original short story.