Awesome discussions. Waaaaay off topic, but screw the topic, this is fun!
The six films are obviously canon, but here is my caveat justifying the existence of the PT: The stories about the GFFA exist, and the films/radio dramas/books/comics/games are strictly the vehicles that deliver those stories. When a film or whatever else brings that story to you or I, the story is delivered brilliantly sometimes and poorly other times. The PT brought us the story of Anakin Skywalker and the rise of the Empire, but it delivered it poorly. I have no problem accepting the various plot points shown in the PT, but the execution of that plot was poorly done. My personal canon is a more or less unconscious exercise which simply bridges the gap between the poor execution of the plot to the details of that era as first recounted in the OT. For example, we didn't see Obi-Wan and Anakin as good friends most of the time - doesn't mean it didn't happen. We only saw what the PT showed us, and it completely failed to show that the two Jedi were good friends, as Obi-Wan claimed. The events in the PT spanned, what, 20 years or something? There was obviously a lot of stuff the films didn't show us.