Zeppelin. Lots of Zeppelin.
Page's production and playing, JPJ's immaculate lines (40 years later, I STILL keep finding gems in his bass parts, like the double stops under the chorus of 'When the Levee Breaks'), Bonham's massive drumming, and Percy's vocals. And the range they covered, for me, was always eye-opening. Plus, it's just my favorite s**t to play REALLY, REALLY, LOUD.
Joey