Gonna have to think this one out.....
First to come to mind is:
Cars: Best decade was the '60s. Cars had style and a signature. You could tell a Ford from a Buick from a Mercedes. Styling was very individual and flowing. From the Avanti to the Camaro to the XKE, almost all car manufacturers were focus on 'cool'. Not to mention the ease of maintanance fo the consumer. Simple engines.
Movies: I'm gonna have to go with the '50s. In addition to the great Hitchcock movies, Hollywood started to get out of the 'actor as property' mentality and actors started to choose films based on their talents. Some great directors started to emerge. Stanley Kubrick, Sydney Lumet, John Ford, etc. And war movies moved on from being strictly patriotic to a sense of realism. Bridge on the River Kwai, Stalag 17, Sink the Bismark, Paths of Glory, etc. And lastly, the sci-fi movie was coming of age. Although there were duds, they were just growing pains. But you can't beat The Day the Earth Stood Still, It! The Thing from Outer Space, Them, Forbidden Planet, etc. A Great time.