I had different favourites at different times.
When I was very small, I loved Alison Uttley's Little Grey Rabbit books, and Beatrix Potter.
Around 5 or 6, I moved on to Paddington, and at 7-9, all the Swallows and Amazons books, Anne of Green Gables and Little Women. At 10, I fell in love with The Once and Future King, The Hobbit and Rosemary Sucliff's ancient Rome books (Eagle of the 9th?) and discovered Sherlock Holmes. Thereafter it was Lord of the Rings and Agatha Christie and then I moved on to adult fiction.
I also read a lot of mythology. I was obsessed by it, for some reason.
I think I was probably a strange child, and the fact that I was an only child until I was nearly 10, and we didn't have a tv until I was 9, probably didn't help! I could read fairly well by the time I started school at 5.
Oh, and in my desperation to find something to read, I picked up my dad's copy of one of the James Bond books around 9 or 10, which led to some discussion between my parents as to whether they were suitable. By that time, I'd read one (Thunderball, I think) and moved on to Casino Royale.