I can still remember the first time I heard a Metallica song...I was in college, meeting some friends in the cafeteria for lunch, and I was NOT into heavy metal at all. The cafeteria had the school's radio station on, and the DJ put on 'Master of Puppets'...I was blown away...it felt like i didn't move for the duration of the song. The instrumental in the middle of the song hooked me. I just remember thinking "This is MUSIC!!!" Other bands have been harder, maybe had some songs that I preferred later down the road, but for consistency, and for bringing 'classical' style structure and Beethoven like power to metal, you've got to tip your hat to Metallica as the guys who really made metal accessable to average joe's, like me.