This one's easy. Since yesterday I said Marc Levy could be called one of my favorite authors, the book I love most is Seven Days for an Eternity. I don't know if the book has been translated in English, though. They really should, in my opinion.
This book is funny, romantic, witty, sarcastic, what's not to love about it? It's about God and Lucifer, making a pact. Each has to send their best warrior on Earth and do more deeds in the name of his "boss". They have seven days and the one that at the end of the week has a bigger score, wins and gets to rule over Earth and human kind for ever. God sends Zofia and Lucifer sends Lucas.
Lucas and Zofia weren't supposed to meet, but they do and, naturally, fall in love. There's one very funny scene where Lucas was trying to be romantic and send her flowers. Thinking any flower will do, he sends her water lilies. He actually filled her bathtub with water lilies. It's a very funny scene, but not the only one in the book.
I love all of Levy's books, but this one for some reason is more dear to me. One thing I love most about Levy's books: most of them have two or three characters that are in all of them. They're not main characters, but they sort of connect the books. Of course, all books except The First Night and The First Day are stand-alones.
So this is my favorite book by my favorite author. What's yours?