I read a book the first time for escapism, subsequent times for therapy & escapism combined.
When I am really down in the dumps and need an injection of hope, I love Mary Stewart’s Thornyhold.
For world-myth-mixing heroism, I love Guy Gavriel Kay’s trilogy, The Fionavar Tapestry. His other books are good, too, and I own them all and have replaced several, but the Tapestry has passed into my library Hall of Fame.
For pure escapism, and a healthy serving of wry humour, Diana Gabaldon’s Outlander series.
For a reminder that people are generally better than I give them credit for, Mercedes Lackey, particularly the Valdemar stuff.
I love historical fiction. My favourite time frame is the Dark to Middle Ages in Britain and Europe, but I go on tangents regularly. So, I keep and re-read Sharon K. Penman, Elizabeth Chadwick (Middle-ages in Britain / Normandy), Barbara Erskine (Scotland, most ages), Jack Whyte (the Arthurian legend from a fall-of-Rome standpoint), and Jean M. Auel (Stone Age).
And the book that lives in my bedside table, for midnight wake-up calls from my subconscious, Women Who Run With The Wolves.
These are the ones that come quickly to mind. There are more, and always will be. If I own it, I’ve read it several times. Or it’s a text book.