I'm speaking from the viewpoint of having seen both these dudes in their pRIME. raKim had aura, he had stage presence, he lyrics were simply magnificent. Every1 knew them. The problem with The R though is that he never kept up to date and that gentlemen is a true sign of gr8ness. U have to stay current and have people gravitating to your product. The R had a 5 year run when he hit winner after winner. I think Nas saw the dispute that Rakim had with Eric B and when Ill Will died decided to never duo up. Now look at him he surpassed The R in every which way. I don't diG the comparison. Nas has a more complex rhyme scheme and a more expansive range of topics from which to speak, but Rakim's subject matter was scientifically, mythically and mathematically on some other ish.
Nas would never say publicly but within himself he knows he's the GOAT.