I like
Go Ask Alice. The character really annoyed me at first because she's so..ditzy it seems.
My favourite books are
Impulse by Ellen Hopkins and
Killing Mr Griffin by Lois Duncan.
Impulse is a really good look into how these three main characters feel, being in a mental hospital. Quite sad though at the end, and terribly confusing at parts when you have to flip to the beginning of the chapter to know who the speaker is for that section. You get used to it after a while. Love Hopkins' style, it makes reading just that little more fun.
Killing Mr Griffin surprised me just so much! I won't spoil anything for people who haven't read it yet, but that is a really great book.
I could say many more..but that list may be long. So I'll end it now.