This is a great thread.
I'm a (sort of) youngun so sadly didn't get to experience the building blocks of our current strains such as Haze, Thai stick, Lambs bread, Panama Red, etc... But the strain that always stands out to me is Jack Herer, followed closely by a cut of Old Time Moonshine i was fortunate enough to be given once upon a time. Only reason the OTM doens't take No 1 is she was a fickle bitch to grow and you can't find seeds anywhere anymore.