I've liked Kajiura Yuki tracks in general from My-HiME and the Tsubasa series. She's done some really amazing instrumentals and her songs in her various combinations (See-saw, YUUKA, Yui Makino) has been nothing short of excellent. I could not believe Yui Makino was singing Synchronicity - Yui Makino is usually rally good on the quiet songs but the Kajiura Yuki composition was fantastic.
Off topic but Kaori's live is SICK!!! I did not believe that such a superb live "pop" perfermer existed in this modern age of digital voice editing for CDs. The "Tsubasa" song from FictionJuntion KAORI (composed by Kajiura Yuki so on topic
) doesn't do Kaori's ability justice at all!