Well, I'm 50 so I listened to the usual hard stuff bitd.  You know Sabbath, Rush, Scorpions, UFO, Judas Priest, Iron Maiden, etc.  But after I got out of the Marine Corps in the early 80's I moved in with a guy that was into the newer thrashier stuff so I was all about Megadeth, Slayer, Exodus, Possessed, etc and then I was room mates with the two guitarist from Wehrmacht which was a very influential thrash band for Portland.  Now I've come full circle.  I really like Alex Lifeson, David Gilmour, and I really think that Dave Mustaine, as popular as Megadeth are, is really underrated.  He blows the doors off of Kirk Hammett.  And I really like Michael Schenker, Frank Marino, and Frank Zappa.