I've read most of them, including the aforementioned Millionaire Real Estate Agent by Gary Keller as well as his latest, Shift. I can tell you without reservation that, IMO, the best book out there currently on real estate sales is Dirk Zeller's The Champion Real Estate Agent. I bought the book when it first came out, almost three years ago, and I still crack it open and refer to it a minimum of three times a week on average. I haven't read a better book out there.
In the interest of full disclosure, I recently (about 6 weeks ago) joined his coaching program, so I guess I could be considered a biased source. But I never would've joined it if I weren't still reaping the benefits of that book, three years later.
Editor's Note Dirk Zeller writes a series of Sales Skills Articles that appear in the RealTown articles area.