Both are true. Aside from the obvious exceptions, you shouldn’t worry too much about how an agent will compare your book with what he already represents. You should instead focus mainly on whether the agent represents books in the same general category as yours, and if you like his taste. An exception to this is if your book is clearly in direct competition with something the agent already represents. For instance, it’s not a good idea to send your proposal for “The Basket Weaving Bible” to the agent who represents the author of The Definitive Guide to Basket Weaving. Of course, with fiction it can be harder to tell whether something is too similar, so you can always mention the similar books in your query and make a point of stating how yours is different. (I don’t suggest mentioning how it’s going to be better!) Here’s an example of what a writer interested in querying me should take away from knowing that I represent Benjamin Percy: His novel, The Wilding, deals with the commercialization of the American frontier and the idea that there is an animalism that lurks within us all. If your novel does deal with similar themes, great—feel free to mention that in a query. I always appreciate when someone has taken the time to familiarize herself with my list and my interests. But you shouldn’t assume that I’m actively looking or not looking for fiction set in the American West or about people’s more animalistic tendencies. Instead, if you like my writers’ work and you think I’d be a good match for your book, then query away. And if I do think it’s too similar to something I represent, I’ll let you know. Either way I’ll appreciate your having done your research.
I’m always reading about how writers should choose agents based on their client lists: If an agent represents an author you like or who writes like you do, it might be a good fit. But I also hear agents say they’re looking for something new, something unlike anything they’ve ever read before. Which is it?