Eh, you'll find someone arguing for every rapper that's a good lyricst as the best one ever. For every decent rapper there is plenty of people who would put him first. Doesn't make it any more belivable.
But seriosly would you put Eminem as the greatest lyricst of all time? If so the fuck you smoking? He's not even the greatest of HIS time, let alone ALL time.
I hate how everything good he does is somehow exhaluted higher then it ever would've been if someone else did it. It's bullshit. And it happens JUST cuz he's Eminem. No denying it.