Response-
I've always been partial to movies about superior robotic AI. The Terminator was just one long robot a** kissing contest with little boys and human women. The focus in the Star Wars and Matrix films was far too much on the humans. So, clearly it is Back to the Future. However it was meant to be a four movie series.
Clarification-
In the fourth movie, Marty learns that the time machine was carefully rebuilt in the future by clearly superior robotic battledroids. He goes into Emmit's lab in search of the blue prints to the time machine, with the hopes of destroying them. However he is greeted by hail of gunfire. Afterwards his entire family is killed by robotic assassins (except for his father who is given a series of purple-nurples that are so painful that he catches fire) . The robots take over the planet and in the end, humanity is destroyed by the robotic scientists who are in fact working with the newly chromed Emmit Brown. All in all, a good film.
I forgot to mention that Bif falls into robo-manure 36 minuets into the film. CLASSIC