(Course, you could always buy these books for yourself, too. You deserve it. Yeah, yeah you do.)
For the fan of drama, darkness, and stories of healing: Pointe by Brandy Colbert. Theo is a mega-talented ballet dancer. She's also recovering from anorexia. Then her best friend, Donovan, who was kidnapped four years ago, is found, and his kidnapper caught. That's when Theo discovers that she knew Donovan's kidnapper. What she could say in court might make all the difference, both to the case and to Donovan and Theo's lives.
For the fan of smart, atmospheric reboots of classics: Of Metal and Wishes by Sarah Fine. It's Phantom of the Opera, but in a reimagined industrial Asia. Instead of an operahouse, it's set in a slaughterhouse. Grim yet beautiful, and you'll root for capable and empathetic protagonist Wen.
For the fan of rapid-fire action and stuff that makes you go "coooool!": Steelheart by Brandon Sanderson. A strange new star appears in the sky, and suddenly people are developing superpowers - and turning evil. These superpowered "Epics" quickly come to control the world. The Reckoners are a group of humans with the mission of assassinating Epics. David wants to join the group to avenge his father, but it's not easy to get in. Good thing he has a bargaining chip - he might hold the secret to taking down one of the most powerful Epics in the world.
For the fan of nail-biting disaster stories: The Living by Matt de la Peña. Shy is spending his summer working on a cruise ship, making a little money and goofing off with his friends on the crew. Then a massive earthquake strikes. Their training didn't prepare Shy and friends to deal with tsunamis hitting the ship. Or with what comes afterward.
For the fan of rollicking fantasy adventure: The Amulet series by Kazu Kibuishi. Maybe a little more middle-grade than YA, but this gorgeous ongoing graphic novel series appeals to everyone. Seriously, everyone.
For the fan of realism with an unusual viewpoint: If You Could Be Mine by Sara Farizan. In modern-day Iran, homosexuality is a crime, so girls in love, like Sahar and Nasrin, have to be careful. And they certainly can't get married. But being transgender is not a crime - in fact, the government will help you get sex-reassignment surgery. Sahar is a girl, and she knows it. But if she could be a boy, then maybe Nasrin wouldn't have to marry someone else. Maybe they could be together.
I'd also like to recommend this Holiday Shopping Guide by Diversity in YA. (They also sing the praises of The Living.)