I agree.
I am surprised that "Witches Abroad" made it in it, but not the other books which are, at heart, an extended riff on various themes (e.g. "Wyrd Sisters"/Shakespeare, Maskerade/opera and live theatre, Soul Music/rock 'n roll, Moving Pictures/films and Hollywood).
Thief of Time, also, is a fantastic riff on various end-times prophecies, everything you ever thought you knew about Asian martial arts, and chocolate.
At the same time, I thought: what about Pyramids? But then, I've recently been reading a history of ancient Egypt.
And what about Sourcery? But then, I've read various books on Norse mythology, which Sourcery punctures brilliantly.
Aaaaaargh! Too many books, not enough time!