FP is certainly the best SF movie ever made, at least until 2001 came along 12 years later, in 1968.
Sorry, but you can’t leave The Day The Earth Stood Still out of the mix, even if it was a few years earlier (1951).
I thought TDTESS was really boring. Could never sit through the whole thing.
The book version was better, though. It was called Farewell To The Master, by Harry Bates.
In it appears the poignant scene, in which Gnut is trying diligently to recreate the dead Klaatu from a recording of his voice saying the only words he ever uttered: "I am Klaatu, and this is Gnut."
His attempt fails because of minute imperfections in the recording. He is able to make a Klaatu that lives a few minutes, but soon dies as a result of these imperfections.
In the 1970s, there was a band called Klaatu that many people thought was actually The Beatles. It was formed after The Beatles broke up, and the desire was so strong among many of their fans to resurrect them.
I don't think very many of the fans of Klaatu understood the connection between the name of the band and the sound they were trying to resurrect.