The Pac/Biggie, Westside/NYC feud was legendary. Although Tupac, in my opinion, was on a whole other level. He brought rap to the forefront of pop culture in his time and is one of those rappers that I think people will be listening to 30 years down the road. Shame he died so young, his was one of those characters that went beyond the music like John Lennon and Kurt Cobain. He also would have been HUGE in acting by now, if you ever watched any of his movies, you'd see what I mean.
Two of Amerikaz Most Wanted:
http://www.youtube.com/watch?v=WsFNXAmGz8U
Hit Em Up:
http://www.youtube.com/watch?v=N4HjsZqOaQ0
If Tupac lived today, I wonder how he would have treated with Eminem (who is probably the second most popular rapper in history); Eminem based his story telling rap style off of Tupac, and he practically worships Tupac. Though mostly because of Eminem's relationship with Dre.