I may be cheating by covering a whole series instead of just one of the novels, but how does one choose a single favourite among such an incredible set of books?
Supposedly written for children, The Narnia Chronicles fill me with as much joy and wonder now as they ever did. They are stories that never, ever get old.
I collected a mismatched set of the books over several years as a child, and then as a teenager I indulged my slightly OCD book-neediness and bought a boxed set with matching covers. I can’t find any of the first lot, and only one of the boxed set remains on my shelf. I’ve lost a few in different classrooms over the years and others courtesy of unreturned loans, so several years ago I bought the complete set in one volume so I could read them all again.
While each book in the series is a unique and brilliant story in its own right, as a collection they are remarkably cohesive and unified.
The Narnia Chronicles really are the works of a master storyteller.
WordyNerdBird 
I didn’t discover the Chronicles of Narnia until I was in my mid-twenties. A friend, a gentle giant with red hair – read them to me, and of course, I was hooked. Since then, I have lost track of how many times I’ve read them.
I remember about 30 years ago, I went to a church with many Lewis fans, and a collection of the books was released in what we all considered the wrong order – that is to say, with ‘The Magician’s Nephew’ as the first book. Though it is chronological in terms of the events in the books, it was the last one Lewis wrote. After the ‘Last Battle,’ with its sadness and haunting happenings, I was always grateful that he wrote one more book, and I would think that new readers would be as well.
Nowadays, I have an audio version of that out-of-order collection on a device called a Booksense, which plays books from several services for blind and otherwise reading impaired readers. The Chronicles come from the National Library Service for the Blind (NLS), part of the US’s Library of Congress. It’s a permanent fixture, and I pop on over to it whenever I need a glimpse of sanity. I also latched on to a small section of ‘The Silver Chair’ to create a legend for my own novel, ‘The Heart of Applebutter Hill.’
Ah, one of my favourites in books. I confess that I relisten to the books on audio every few years.
Audiobooks are excellent!