For me, it's the 70s, even tho it's the decade when the axe fell for the global left, the eclectic fashions, the vibes, the simultaneous sense of cultural defiance, despair, emerging technologies and building dread of an unknowable future that we now know so well, gives it an almost otherworldly quality other decades lack
Also best decade for hair
The 70s. For me there isn't a close second. I'm heavily biased though. I was kid/teen then.