"Counting the Days To Armageddon" by Robert Crompton is an excellent piece of scholarship that trawls over HOW they came to the dates and chronoogical systems they did .... and why they were later changed. It taught me (like most of these books did!) much more abut the religion and its teachings thn any WTS publication. Crompton's book is a real eye-opener. It's very thorough and dissects the origin of the teachiungs all JWs just take for granted.
Also check out "Crisis of Allegiance" by James A. Beverley. He is a non-JW and the subject of the book is the ructions that took place in Canada surrounding the expulsion from the religion of James Penton. He highlights what a nasty, conniving bunch of a-holes the WTS leadership and middle management is and the lengths they went to in order to achieve their goal of getting rid of someone who dared to question their teachings.
For anyone interested in the early organisational and doctrinal development, "A People For His Name" by Tony Wills is also excellent. It again is very well researched and very thorough.
"The Orwellian World of Jehovah's Witnesses" by Heather & Gary Botting is a fun read that hammers the point of the similarities between the WT organisation and Big Brother in its information control and dictatorial methods.
Beckford's book is very good though a little dry in parts, Holden's is excellent as well -- both of them analyse the thinking and behavior of Witensses as a group and why they act that way, and they provide many lightbulb moments as you realise they're describing your own behavior of the past.
Those books should all be required reading for JWs so they can gain a better view of the life they have chosen to lead. Unfortunately because many of them contain information that's critical of the religion, JWs will never read them, because they've been trained not to read critical material. I'd love to ask a JW how many people they meet at the doors where people won't change their religion because they never fully analayse it. (JWs would always say, "Yeah, people are born into their religion and never examine it. They're so close-minded.") And then ask them if they've ever read books by outside sources that examine their religion. Ask them if they're allowed to read such a book. And what they have to fear. And what it says about their religious leaders who forbid them from reading books that criticise their religion.