Real diversity. Not just token sassy gay/black/hispanic friend.
Then, check out these:
GLBTQ teens in fiction. I can personally and enthusiastically recommend Melissa Marr’s Wicked/Lovely series, The Gemma Doyle trilogy, and the Holly Black series.
Racially diverse teens in fiction. Authors A - L. I loved How to Ditch Your Fairy and no body does it better than Ursula Le Guin.
Authors M-Z. Run, don’t walk to read Margaret Mahy’s Changeover and the sublime Haroun and the Sea of Stories