hmmm..... i dont know,you cant really be unknown for an entire areer and truly be considered great.. greatness encompasses so many qualities and among them is sheer impact, longevity, and consistancy.... and while there may never be a "greatest", we will all have the ones who shine as the greatest to us, and in our own careers as influences.
one thing i will say, is after this last album, Ghostface has to be considered... he has to be mentioned.... he has to be accounted for... duke just dropped his fourth and they have all been somewhere between classics and simple excellence. can anyone really deny that much? he hasnt ever put out a bad album. 4-for-4 is a damn good track record, is it not? solid, all the way through, and he has maintained an odd balance of underground with a bit of mainstream accessability (although not superstardom) in the process.
my top three.... FOR ME, forget all time, that will never be conclusive- is Ghost, Common, and Andre Benjamin (eff that "3000" suffix...). those guys are my greatest influences-with an obvious nod to the production teams involved. those three, are in my eyes, the best ARTISTS in hip hop in my eyes.