For those of us over 60..

I'm not quite 60 but for me it's the ABB followed closely by Cream. I still own much of the vinyl I bought in the 1970's, The Allman Brothers Band, Idlewild South, and Fillmore East and Disraeli Gears. I own quite a bit of fusion and funk from the same period - Billy Cobham -Spectrum is an almost weekly play as is The Mahavishnu Orchestra - Birds of Fire or Between Nothingness and Eternity. Probably should mention Santana also, first LP for me was Santana III.
It's probably not a surprise that I am currently running stacked "Large" 1973 Advents as my mains (also owned since I got them in the '70's)

Judy Collins, Joan Baez, and Dylan (I'm 79). :-)

Steppenwolf

so, topping 70....what was the question?....how in hell did I get in here?....oh, Jimmie Rodgers...in Nashville at Country Music Hall of Fame in 70's...sat alone in a little area watching "Waiting for a Train" historic film, thinking, "This is my lifetime opportunity to view this."  Now, double-click and there it is on YouTube.  Take a look.  Joni, Richard Thompson and Greg Brown help me through life...oh, the question, Little Feat "Waiting for Columbus" tour...big system, small venue University of Alabama...best rock sound evah! (from Maine)  Oh Lowell, what you were and could have been. 

For me it’s Pink Floyd