Most Helpful Girl
"The Perks of Being a Wallflower" by Stephen Chbosky
"Looking for Alaska" by John Green (also basically any/every book by him, haha, "Paper Towns" and "Will Grayson, Will Grayson" are also really good)
"I am the Messenger" and "The Book Thief" by Marcus Zusak
"Youth in Revolt" by C.D. Payne (not necessarily a "young adult" book, but it's about a teenager, plus it's the funniest book I've ever read, haha)
"The Catcher in the Rye" by J.D. Salinger is also not necessarily a "young adult" book but seems like an obvious choice, lol.