Let me put this another way: Before Rakim, all rap was like listening to a jazz saxophonist playing everything strictly within the structure of "Mary Had a Little Lamb"; after Rakim, rap sounded more like John Coltrane's "Giant Steps." With an elasticity that was completely new to the form, Rakim could expand a rhyme to a dizzying length in one line and then compress it into a microsphere in the next. The essence of his accomplishment was to transform rapping into an instrument. I will now get right down to it and say that Rakim is the greatest rapper of all time.
My position now stands on the solid ground of this image, which appeared on the web last week: