4. DJ Mustard & TeeFlii, 'Fireworks'
Los Angeles producer DJ Mustard has redefined the West Coast with instantly identifiable beats that blend the tempo and rubbery bass of classic California hip-hop with the sound and space of Atlanta snap. He released his own mixtape, the aptly and arrogantly titled Ketchup (get it?) this year, but his best effort was Fireworks, a collaboration with the singer TeeFlii, who looks like a lost Debarge sibling and sings like The-Dream's bratty younger brother. Where Mustard’s beats normally evoke a strip club's booty-whomp, here he pushes himself, brilliantly, towards R&B smoothness.