I respect everyones opinion, even though if you hate the genre. It's a free country, if some people don't like rap then that's fine too. But Rap haves a very long and successful history and may I add has gone through many changes over the years. I for one dislike some types of music, but I don't ever say I hate them.
Anyways
The greatest of all time to me is 2pac, because he was true to his self and was the most down to earth man I every heard musically and personally. He was the most influential, controversial, believable, rapper who'd express the reality of things. He was not only a rapper but also a concern man who politically and socially wanted to see changes in this world, especially from what he had to endure as a child, which has given him extra creditability. Not many people know this side of 2pac. Also, from what I've seen on youtube, He was a Christian, which had an impact in some of his songs and in some of his lyrics. In addition, the man deserves some credit for being the only rapper who has past away and still be alive today. Over half of his fans believe that he is still alive, so that being said he has made a great achievement on the behave of rap and hip hop. R.I.P Tupac
Eminem He is lyrically one of the best even though I don't agree with none of his lyrics, but I have to admit it.
Lauryn Hill Poetically the best female rape artist
Common This guy is poetically talented
NWA most influential group, who'd basically change the movement of rap. ( I do not like the NWA, I personally believe they were too negative along with many others today)