Per
evil_little_dog asks what my favorite three YA novels are. I'll raise you one and talk my three favorite YA series. In order of preference:
1. Diane Duane's
Young Wizards. They're a different and fascinating take on magic as a whole. Her wizards are basically manipulating the forces of the universe via what could be described as sufficiently advanced science. Duane works world mythology, philosophy, religion and cosmology into her books, and the results are fantastic. She recently updated some of her older books so you wouldn't get a Dictaphone and an iPod in the space of just a few years linear time (the first books were written in the '80s), and I really hope she's planning to write more of this series. There's also a spinoff series about feline wizards which manages to be more adult in tone.
2. J.K. Rowling's Harry Potter series. Predictable, perhaps, but it doesn't change the fact that the books were game-changers. She created a beautiful, intricate world and drew innumerable people into it, and I think these books will be around for a long, long time.
3. Rick Riordan's
Heroes of Olympus series. It's spun off his popular Percy Jackson series, and I think it's a definite leap in quality. The writing is better and the world is more complex, drawing in Roman gods as well as Greek ones. These books have managed to draw more young people into studying mythology, which was probably part of his Evil Plan all along, as he is an English teacher. He's also tackled Egyptian mythology in The Kane Chronicles, and I've heard he's planning to take on Norse mythology next. Here for that!