The greatest lyricist of all time is, IMO, Dante Alighieri.
Oh, you meant rap lyricists? I can't be bothered to rank them as long as Bob Dylan still makes music.
"The Devil is not the Prince of Matter; the Devil is the arrogance of the spirit, faith without smile, truth that is never seized by doubt. The Devil is grim because he knows where he is going, and, in moving, he always returns whence he came."