I have not yet had the opportunity of judging any of them objectively, since the truth of a theory can only be demonstrated after it has been proved. However, once proved in practice, a theory is often no longer valid as such. It is highly problematic to attempt to prove something that has already been demonstrated - except probably in Euclidian Theorems, when QED would apply.
For that reason I can, for the time being, only accept the fiction of 'The Pelican Brief' (Denzel Washington) and 'Conspiracy Theory' (Mel Gibson) - the cast are so experienced, and Julia Roberts makes an appearance in both.
For me, the Report of the Warren Commission, the continuing saga of the Grassy Knoll, the Last Days of Marilyn Monroe, and the staging of the Moon Landings are too much like well written film-scripts.