I keep seeing people recommend the same handful of books, and honestly, most of them are fine but kind of predictable. 'The Song of Achilles' and 'Circe' are the obvious giants, and they're beautifully written, but they're also adult literary fiction marketed to teens. For actual young adult pacing and voice, you have to look elsewhere.
Madeline Miller's work is a gateway, but the true YA heart is in series like Rick Riordan's various pantheons. They're foundational for a reason. The 'Percy Jackson' books are the entry point for a whole generation, mixing modern humor with myth. Beyond that, I found Katee Robert's 'Neon Gods' is… not for teens at all, despite the myth branding, so watch out for that. A quieter pick I loved was 'Lore' by Alexandra Bracken. It's a standalone with a gritty, modern hunger-games-style take on the Agon. The mythology is woven into a contemporary thriller setup, which feels fresh.
What I look for is a protagonist who isn't just a passive vessel for the gods' drama, and 'Lore' delivered that for me. The ending felt a bit rushed, though.