First off I wanna point out you yourself just said the worst song on Illmatic is a 5/5 song. The worst song on IWW is NOT a 5/5 lol. Nas Is Coming and Black Girl Lost are worse than every song on Illmatic. I rest my case.
I say Illmatic is more diverse lyrically because it is far more poetic and evocative. Thematically both albums are about street life, sure. But in my opinion Illmatic is much more personal, descriptive, and honest. The similes are more vivid. There's nothing on IWW, or virtually any rap album, more jarring and impressive than "drink moet with Medusa, give her shotguns in hell from the spliff that I lift and inhale." In a genre surrounded by rappers getting off variations of "I'm so cold I give chills," this man said I'm so cold I can look Medusa in the eyes and not get frozen. Come on. Then there's shyt like the last verse on One Love. Speaking of which, I think that narrative device is more impressive than I Gave You Power because no one had done it before, on any level. No I'm not going to say Nas bit Stray Bullet because he didn't. But it's an inanimate object given life, nonetheless. Nas gave his object actual personality and emotion, which is the biggest difference to me.
Just pulling up the track list of IWW shows you how focused it is on mafioso raps. It's less personable because it's more about a character/persona. And while the character is interesting and the rapping is great and there are multiple classic tracks...I can't call it better than Illmatic when it's not even the best mafioso rap album. Cuban Linx is better and more imaginative IMO.
just my opinion