It's really hard for me to pick 1 book because I like to read a lot and I read a lot every day. I don't feel comfortable if I didn't read a book at least 30 minutes before I go to sleep. I read everywhere: at home, in metro, during bus ride, in cafe while eating and drinking..
I have a lots of favourite books so instead of picking 1 book I'll pick my favourite author.
Joanna Chmielewska is a polish writer. She wrote crime fiction and comedy, her work is often described as "ironic detective stories". From 1964 to 2013 63 books were published. I've started reading her books around 12 years ago at age 12 so not only her books are fun to read but they also taught me a lot of stuff.
I've read some of her books more than 20 times. And when I feel sad or depressed I always read 2 or 3 of her works.
She was an amazing writer and an amazing person, I'm more than 100% sure that her books will be with me during my whole life)
From what I know her books are not published in english but they are probably translated by fans.