the reason is because they both got shot and it is the Fallen Artist Response that we see time and time again. After someone dies young, they are automatically the best ever (Biggie, Pac, Kurt Cobain, Jimi Hendrix, the list goes on) . Well, with Biggie and Pac, it happened around the same time, so it has been a big debate for a decade, but it really doesn't matter anymore. People need to realize that it is their own personal opinion and you don't have to fight over it anymore. People think that their favorite rappers have to be Big or Pac, when it doesn't. My favorite is Common. But most people just think that one of those too has to be the best by default. Open your minds people.