Harlan Ellison "I Have No Mouth and I Must Scream."
The Ellison story is graphic, sexually and gore-wise. If you don't want to read it you don't have to. It's intense and amazing.
Robert A. Heinlein "All You Zombies."
The Heinlein story concerns sex but doesn't have sex scenes. You can skip it if you want to, but you'll be missing out on the most amazing story ever.
Norman Spinrad "Carcinoma Angels."
Bob Shaw "Light of Other Days."
So happy I can include a lesser known master like Bob Shaw.
Disregard this one for now.
Damon Knight "Backward O' Time." PDF file on Moodle.