There's always a conflict when it comes to whos the best rapper alive, but it's pretty much accepted that Eminem, Nas, Jay-Z, Big Pun, 2pac, Big L, and Biggy were the greatest rappers to ever live. When it comes down to lyrics, flow, and impact on the genre it's usually Em, Big and 2pac chosen from those few I listed that are named.
When it comes to Big, Eminem, and Tupac Shakur, who do you think was the better rapper/songwriter/over all artist and also WHY? In my opinion 2pac was. Three classic albums in a row (Me Against The World, All Eyez On Me, Makaveli) and his influence on rap is still alive today. He touched on alot more subject matters then BIG and Em although you could make an argument that it was because BIG's career was alot shorter. Eminem had classic albums too, but even as a die hard Em fan I have to say that Relapse and Encore were pretty bad and hurt his legacy. Also it's cool he loves his daughter but damn, he makes so many songs about her it's almost like he uses it to sucker people in with emotions. Recovery was a great album at the time but it doesn't have classic replay value like Ready To Die or All Eyez On Me have 15 years later. Also 2pacs work ethic was light years ahead of BIG's. When BIG died he had not even 12 unreleased songs which only 3-4 of them were actually good. 2pac on the other hand had over 200 songs done unreleased at the time of his death. Classic records like Changes, Unconditional Love, and Until The End of Time were throwaway songs he never intended to release yet became huge hits.