Yeah I'd have to say Phillip Pullman's His Dark Materials is BY FAR the best I've ever read.
Also agree with the Isobelle Carmody's Obernewtyn Chronicles and Pratchett's Discworld.
Others I love are Anne McCaffrey's The Chronicles of Pern and the Acorna series, all of Ian Irvine's Tale of 3 Worlds series, Robert Jordan's The Wheel of Time, Tolkein's The Lord of the Rings , Douglas Adams' The Hitch-hikers Guide to the Galaxy , Brian Herbert's Dune series (The ones writtten by his son I dodn't like as much) and of course C.S Lewis' The Chronicles of Narnia , which was probably the first series I ever read, and I could never say that they're not some of my favourites!
Hmmm and I'm supposed to be doing my HSC this year...Maybe I can just get paid for reading all of my books over and over?