That 'best' label always throws me. Thrilling survival stories live in so many subgenres, and my favorites shift with my mood. For a pure, classic man-vs-nature ordeal, it's hard to beat 'The River' by Peter Heller. It's this minimalist canoe trip gone horribly wrong; the tension isn't from monsters but from a snapped paddle, a missed landmark, and the creeping knowledge you're utterly alone. The prose is so clean and sharp it makes you feel the cold water.
Then you've got the 'society collapses overnight' niche. I devour that stuff. 'One Second After' by William R. Forstchen is brutal because it's so plausible—an EMP knocks out everything, and a small town has to figure out how to survive without power, medicine, or law. It reads like a manual for the end of the world, which is terrifying and weirdly fascinating.
If you're okay with a fantastical setting, 'The Luminous Dead' by Caitlin Starling is survival horror in a cave system on another planet. One caver, one person in her ear, and a suit that's both her lifeline and her prison. It's claustrophobic and psychological, more about surviving your own mind and the person on the comms than the environment. Makes you think twice about going into any dark hole.
And for a deep cut, 'The Raft' by S.A. Bodeen is a YA take that's surprisingly relentless. Plane crash, two teens on a raft in the Pacific. It's short, mean, and doesn't pull punches about dehydration and sun exposure. Sometimes the straightforward ones hit hardest.