The Louis Malle was not-so-great due to the silly premise, but I still thought it was fantastic.
When he gets locked inside the elevator I said aloud: "Ooh this is gonna get interesting!"-- and it did. A murder plot within a murder plot!
I felt it was silly that he left his grappling hook at the scene. Some hitman!

The Polanski debut was well-shot and taut- you never quite know where the story leads, with a nice twist (of the knife?!) at the end.