There will never be a definitive GOAT regarding lyricists in hip-hop. As the rap genre has broadened, the qualifications that constitute a potential GOAT candidate have become too multitudinous, making it impossible for hip-hop heads to arrive at an objective answer. If you're focused on sales, Drake could easily qualify as the GOAT. Let's say critical reception is more of your bag. Kendrick Lamar or Tupac could both earn a spot at the top. The conversation becomes even more complex by including topics like flow, cultural impact, staying power, raw lyrical ability, etc.
As a result, rap fans have started to anoint multiple GOATs that correspond to different eras. In modernity, Drake, Kendrick Lamar, and J Cole have been designated as the three kings of mainstream hip-hop. However, in the video linked above, the YouTube channel Dissect Podcast illustrates why I believe that J Cole should exist as the definitive GOAT in contemporary hip-hop.
Here's the entire verse featured in the video, by the way.