So hard to get this down to five but here are mine:
Conspiracy - Anthony Summers
Oswald And The CIA - Newman
Our Man In Mexico City - Jeff Morley
Marina And Lee - By Mrs Oswald
The Death of A President - William Manchester
What are yours and why?
I don't think I can break it down to just five, and I'd organize the list a different way. These are what I would call the essentials:
Foundational Works The WCR
The HSCA Report
Death of a President -- Manchester
Marina and Lee --McMillan
First Generation Criticism Rush To Judgement and A Citizen's Dissent -- Lane
Accessories After the Fact --Meagher
Inquest -- Epstein
Six Seconds in Dallas -- Thompson
The Garrison Case On the Trail of the Assassins -- Garrison
Counterplot -- Epstein
American Grotesque --Kirkwood
The Garrison Case -- Brenner
False Witness -- Lambert
Let Justice Be Done -- Davey
Later Books that Summarize Later Conspiracy Thinking Crossfire --Marrs
Conspiracy/Not in Your Lifetime -- Summers
JFK and the Unspeakable -- Douglass
(I should add)
Rebuttals to WC Criticism Reclaiming History -- Bugliosi
You Be the Jury/Final Disclosure -- Belin
Case Closed -- Posner (BTW, CC is the weak sister in this threesome)
Stuff About Stuff About the Assassination A Cruel and Shocking Act -- Shennon
Praise from a Future Generation -- Kelin
The Last Investigation -- Fonzi
Collections of Source Material The WCH
The HSCA Hearings and Appendices
Pictures of the Pain -- Trask
The Killing of a President -- Groden
In the Eye of History -- Law
There is one more book, that I think is the best JFK assassination book ever, not because I agree with it's conclusions, but because it takes a fairly outre' notion and makes a surprisingly gripping personal narrative about it. That book is Best Evidence.