A few things I love: anything Ted Chiang, with a special spot reserved for Story of Your Life (Arrival):
I read Story of Your Life for the first time when I was fifteen, and every few years since then. It only gets more and more devastating, life-affirming. A great lifelong touchstone.
David Zindell’s Neverness books are incredible for their presentation of philosophy and religion. M. John Harrison’s Light is beautiful writing, true literary SF.
It’s fantastic! I don’t think any other novel has given me as much of the almost physical sensation of having my mind stretched and twisted.