I keep a spreadsheet just for this niche. Strong first-person voice isn't just about 'I' statements; it’s about the character’s worldview warping the prose itself. 'The Catcher in the Rye' gets cited, but Holden’s cynicism is almost a genre template now.
More recently, 'Eleanor Oliphant Is Completely Fine' nails a voice so distinct you can diagnose the character through her syntax. The deliberate, overly formal phrasing mirrors her social isolation. Same with 'Convenience Store Woman'—the protagonist’s internal logic about store routines becomes the novel’s entire rhythm. It’s less about plot and more about how a mind organizes reality.
For unreliable narrators, 'The Secret History' filters everything through Richard’s romanticized, guilty lens. You’re stuck inside his head, so the elitism and horror feel justified, even beautiful, until you step back. That dissonance is the point. My dark horse pick is 'Piranesi'—the narrator’s gentle cataloging of the House creates a voice that’s both innocent and profound, turning a weird setting into a character study.