I listed a bunch of "favorites," but I still think it's a strong word, haha. I like the books I listed, and have re-read many of them (never recapturing the magic of the first read), but I have this sense that my favorite book is still out there waiting for me somewhere...
I will put down a free or cheap e-book if I'm doing too much eye rolling in the first few chapters (sometimes pages), but some books I force myself through. If everyone is raving about a title, or it's the latest best-seller, or a movie is coming out based on the book and my friends want to see it (I'm definitely a read before watch kind of person), then I will endure. Even if I don't like it, I want to be able to explain why I don't like it...all the way to the bitter end!
And I'm totally with anna.wahnsinn - a good (not necessarily happy) ending is critical! However, I like a little bit of ambiguity in an ending...If I'm unsatisfied by an ending, the story continues in my head. Like the story sticks with you for a while. Which is always the sign of a good book.
For those of you who like historical fiction...have any of you read The Paris Wife? It's one of my all-time faves (though didn't make it on my q, lol) about Ernest Hemingway's first wife. I think it's the only historical fiction I've read and enjoyed!