With a legacy spanning soft rock, disco, prog, and fusion, Chicago manage to pop up all over the place. Where Groove Collective's brassy acid jazz incorporates their silky funk, Bruno Mars' retro R&B flirts with the lush synthesizers heard on their '80s ballads. Green Day's “Brain Stew” also demands a shout-out—after all, Billie Joe's chunky riff recalls the Chicago jam “25 or 6 to 4.”