I must admit I was a bit annoyed by the rather crude, inflexible ape masks in Planet of apes and an introductory part of 2001: Space Odyssey, playing with some highly dubious scientific premises (the pre-human hominids looking unconvincingly and living in the barren desert, hunting South American rain forest tapirs).
However, when I put aside these rather technical, minor flaws, the movies were spectacular and left a lasting impression on me.