For me, it was old Kiss songs, especially off the 'Creatures of the night' album, which was much heavier than the others. I always loved the sound of the rhythm guitars on that one - I never cared much for the "meedly-meedly" stuff.
Apart from that, the guitar sound that really blew me away was Hetfield's on "Justice". Yes, I know...that album is poorly mixed, but the guitar sound is good IMO - extremely scooped, punchy and at your throat. At this point I really started working on technique. From the same era, "Nightfall" by Candlemass also has great guitar sounds.
Then when Metallica went mainstream (black album) I turned to Slayer. I always hated their guitar sound but admired their playing.
It wasn't until I heard Yngwie that I got interested in leads. =P