Being based on an actual event can clearly help a film. Sometimes real life is weirder than what is easily made up, and you can show with impunity very weird "real life" stuff no scenarist would dare write, as long as you can back up that it actually happened. And sometimes, you can just make shit up and pretend it's based on actual events, which is ill advised (or at least frowned upon) when dealing with a crashed airliner, but is par for the course with haunted house stories and such supernatural horrors.
But each dramatization, by its very nature, will always include at least some distortion of the truth. Details need to be skipped, shortcuts need to be taken, and explanatory speeches added. It can be a tightrope act, an art even.
Which brings me to the question of the week: what is, in your opinion, the best based-on-a-true-story film ever made? And what makes you like that one so much? Was it the realism? Were you close to its subject? Or where you impressed with the way necessary (or unnecessary) liberties had been taken with regards to the facts?
Chime in, in the comments below, and HAVE YOUR SAY!