If we're talking purely selfish, sybaritic pursuits, then 1974-75. Sex, drugs, rock and roll, more sex and more drugs. I was stone broke and still managed to go to every concert I wanted to see, nail babes right and left, work and sleep as little as I wished and still do just fine. I suspect youth had something to do with it.
As I have aged, I've gotten a changed perspective, and in terms of security and stability, right now is probably that time.
Sometimes I wish for 1975 again, though...