My favourite individual book is "Jonathan Strange and Mr Norrell", by Susanna Clarke. It's written in an imitation of the writing style popular at the time, not only the dialogue and so on but the (abundant and extremely in-depth) footnotes.
It builds an entire alternative history of England as it would have been if magic, fairies and so on played a role in the world, all through footnotes and characters' off-hand references.
Mainly, though, it deals with "present-day" England (during the Napoleonic wars), and in that time magic had faded from England and was no longer practiced; only studied - "theoretical magicians"; scholars and historians both but certainly not
practical magicians.
Eventually we meet a practical magician in Mr Norrell, and from there events unfold - his entering London high society, his services to the government in fighting the French, etc.
Once that's established, Mr Norrell takes an apprentice, the titular Jonathan Strange, and from there on the novel is about the different outlooks on magic of the magicians. Mr Norrell wants to keep it an elite tool in the service of the government, as respectable as the law or medicine, subject to oversight and heavily controlled (preferably by himself) and takes a lot of persuading to accept Strange as his apprentice. On the other hand, Strange represents the chaos of English magic: summoning and working with fairies, going mad and taking up residence in a tower surrounded by eternal night and the freedom for everyone to have access to magic.
Between all that, there's also the story of a black servant to Sir Walter Pole who finds himself afflicted with the affection of a quite mad fairy, and that fairy's own relationship to the two English magicians.
I realize I'm rambling and not making the book very attractive, but everyone should read this. It's impossible to classify as merely "fantasy", "historical fiction" or anything else. Doubly recommended for English readers, especially those who enjoy classical English fiction.
In-universe reaction to the publication of this book from the two magicians:
http://www.jonathanstrange.com/copy.asp?s=2&id=11
http://www.jonathanstrange.com/copy.asp?s=2&id=12