Back to the future 3
I always remember this as being the weakest of the three, and it really is. Don't get me wrong, they had to get away from the times they had been before and the western makes total sense. I remember seeing part 2 as a kid, one of the first movies I ever saw at the cinema, which included the trailer for part 3 at the end and being really excited.
Too much Doc Brown in this one. The romance was nonsense, badly done. The Irish ancestors were dreadful. But the first part where he gets back to 1885, and the last 20 minutes, were really good.