Peckish

The problem with finding the "best" author, book, technique, etc. is that there are many different techniques and styles to this kind of quilting, and they all have pros and cons. It's rather difficult to recommend just one, especially since we all have different skills, styles, and preferences.

When I started thinking about making my own art/landscape quilts, I checked out every book I could find on the topic at the library, and the library system in my neighboring state, which fortunately has a generous sharing policy with my county. I did a bunch of research online, also. Check out the book section on Connecting Threads; you can preview every project in every book they offer. There are soooo many tutorials, free projects, and classes online, you should be able to find an author whose skills and talents are a good fit for you and the style you want.

applique

I agree, the technique will help you choose the "best" author for your purposes. Just an example: mine is realistic, satin stitch and lots of detail. I have done lots of McKenna Ryan and Toni Whitney patterns and also quilts from photos. Narrow down what you like and it will be much easier!