Probably Dragonfly. It's not a world class movie or anything. Most of it was draggy as hell. But then that ending hits, and it's worth it.

But I don't think that a second watch would have the same wow factor at the end. Knowing it's coming, and still having to slog through the first half, I don't believe I'd enjoy it.

Edit: or gone with the wind. Great movie, but it's gotten harder to ignore the flaws in the story despite the movie itself being a masterpiece. I think if I watched it again now, knowing more about the era and the bullshit that got crammed into the book that showed up in the movie, I couldn't be immersed in it.