Reclaiming History by Vincent Bugliosi is the most thoroughly researched book on the JFK assassination ever published. It should be required reading for both pro conspiracy and anti conspiracy viewpoints. Granted it is huge,{1600 pages}, but it addresses virtually every facet of the killing. In addition to all of the usual suspect groups i.e. Mafia, Cia,FBI,Castro,etc, he analyzes the Warren Report.all of the forensic evidence,autopsy findings,Oswalds personal history,including his time in Russia and his military records (including the results of his rifle range tests).
The Tippit murder, the attempt on General Walker, Jack Ruby's backstory, the depository timeline, and tons of more info.
I think it gives the reader more than enough to make their own informed decision.