TOD:
In theory, I love a good crime and keeping up with the developments. In practice, I don't think I've ever stayed with one all that long. Certainly O.J. Simpson for a while, but not consistently and not throughout.
How about the JFK assassination? I loved reading up on all the earlier theories, evidence, etc., but finally dropped it by the time the '80s rolled around and new suspects and theories were popping up every month.
Watergate might actually be my favorite of all. A wonderful cast of characters, and superb entertainment with twists and turns every step of the way.