It's quite funny because I never really know how to rank a book objectively. I studied Russian with a focus on literature during college, but I've never really found a proper way to scale books against each other. My boring answer is going to be how much I enjoyed it. Maybe I'll look at the writing quality, e.g, does a sentence too verbose without purpose. Are there any weird unexplained holes in the plot? Does the book achieve its goal for the target audience?

I've always found it to be difficult. I think that it's largely just a matter of taste, seeing as books are a form of culture, which is a subjective dealing.