18. Killer Mike, 'R.A.P. Music'

On his explosive sixth studio album, Atlanta rap veteran Killer Mike takes hip-hop back to its rebellious roots. Over the impeccably engineered, bombastic production by El-P (who also had one of the best years of his career) R.A.P. Music tackles politics, racism, police brutality and the state of hip-hop itself with an urgency and ferocity that recalls the heyday of N.W.A. While others rappers spent the year bragging about their clique and submitting to EDM trends, Killer Mike has passionately cemented his status as one of the genre's most important players. -- Adam Horne