Nimbus
Holy shit, that was awesome. PiGPEN was too silly, but unrelentingly accurate with the content. Nimbus, however, was on point with the content and the flow. It was if PiGPEN was throwing disses with light slaps and Nimbus had closed fists. If PiGPEN was more rigid with landing the rhymes on time, this would be a close call, but Nimbus is much more of a contender.