Tupac - He was an influential figure AND an artist with a diversity of styles, extremely intellectual music at times. The work rate was insane, he would be finishin albums in 7-8 days - and they are classics. Nowadays it takes them a year to bring out an album which will be forgotten soon.
Just listen to " Weed got me Krazy ", and you will hear real talk - political views - next level poetry - and some skills only he could do.

Eminem's old music was alright and better than most, but cannot touch Tupac.