Planet of the Apes
Dated, but no amount of clunky special effects and stunted action scenes can ruin the simple power of the story.
There are probably very few people who go into this without knowing the twist ending and yet Heston’s performance in the closing scenes still make it all worthwhile.
Perhaps the most effective scene is the trial, where the apes expose their own hypocrisy while stubbornly refusing to see the situation for what it is.
Not a masterpiece, but nevertheless a memorable (and infinitely quotable) classic.