What do you mean by “best”?
Those are the best at parroting the Warren Report.
Well, those you have the widest appeal. Someone like David Lifton might have appeal, but he wouldn't have a wide appeal because his theories are so left of normal - ie Zapruder film was faked, JFKs body was switched.
When it comes to having the widest appeal, Posner probably wins hands down. At least you can read his book unlike Bugliosis "Reclaiming History". McAdams' book is not well known. Doubt if the public at large ever heard of him.