Harry Potter and the Prisoner of Azkaban. I still reach for it in times of stress like the death of a loved one. It's like a cosy jumper.
My first favourite book was Fantastic Mr Fox by Roald Dahl. Percy the Park Keeper, the Ivy Biscuit series and The Lighthouse Keeper - he had a big ginger cat called Hamish.
Danny Champion of the World, Matilda, Charlie and the Chocolate Factory by Roald Dahl. I also loved Jacqueline Wilson books like Tracy Beaker. Oh and Dick King Smith - Saddlebottom!
I loved the Famous Five, St Clare's, Mallory Towers, Adventures of the Wishing Chair, Magic Faraway Tree, Five Find Outers and Dog, The Naughtiest Girl, The Secret series (Jack, Mike, Peggy and Nora) and other Enid Blyton ones - the group which consisted of four kids (Jack, Norah, Mike and Peggy and later Paul the Prince) and The Adventure series (Jack, Lucy-Ann, Philip and Dinah with Kiki the parrot and step-dad Bill Cunningham who was some sort of Spy).
I didn't like The Secret Seven much, and I didn't like Beatrix Potter books at all.