After reviewing another Buffy book I tend to look at YA fantasy books with an eye towards symbolism, although typically I read them naively, just for the story. (What, Narnia has Christian over tones? is my typical level of understanding.) In the Cybils Fantasy and Science Fiction (Young Adult) finalist Guardian of the Dead, by Karen Healey, Ellie Spencer has to look up from her teen-aged angst over her looks and her boy friends to confront mythical creatures with deadly intentions, her own developing magical powers, and the temptation to use a mask as powerful tool to control the people around her.
Nothing like coming to realize that everyone around you has their own motives and needs, ones that may not be friendly or accommodating to you. Or that you do indeed have strengths and abilities that can affect the world in real ways. Or that as a woman, you can use your image and body to control people's reactions in ways that have nothing to do with your real self. No, nothing about that at all.
This was an interesting book that felt richer and more layered than the action-packed Brain Jack. So far it heads this list for me; I'll offer it to my sixth grader but it may be older than his interest level. A-