Lyricism: Eminem. Raekwon is a good lyricist, but he can be bland sometimes.
Flow: Eminem. See above, regarding Raekwon.
Versatility: Eminem. Rae has refused to do anything but coke rap for 20 years.
Creativity: See above.
Discography: Eminem. All Raekwon has is OB4CL, while Em has SSLP, MMLP and TES.
Lyricism: Tossup. Both are hardcore lyricists. One is a street commando with wordplay out the ass, the other is a crazy ass kid from the trailer parks..or is it the burbs across the street from the trailer parks? Either way, both 'in their prime' were hardcore and pretty much everything about them is legit. Both have had their stumbles, but even on 'bad' tracks, these two usually have shining verses.
Flow: Tossup. Rae's VOICE is too sick, while Em has the tongue-twisting 'fast' flow at times while Rae only seemingly has one flow. Both hypnotic flows, and while I could lean Em I'm going toss up because Rae has one of the all time best rap deliveries and voices.
Versatility. Not even close. Em by far. The guy's got a persona. Plus he's done everything, been on tracks with everyone. Rae did a track with Bieber, but it still seemed like Rae being Rae. Eminem can step out of his comfort zone. While a lot of all that shit isn't that good.. I still give the nod to Em because of it.
Creativity: Tossup. Em is creative as fuck, but his best days were basically drug raps too. Drug addict raps. That and beating up his mom killing Kim and what not. I think both create vivid pictures. For that I can't lean one side or the other.
Discography: So we're going to just forget about Wu Tang Forever? And 36 Chambers? You've also gotta put Ghost's Ironman in there, because it's basically a team effort there. I think Raekwon's body of work is legendary. Eminem has great albums, and a lot of them from his "slim Shady" days that all follow that theme, but it gets played out. There are a lot of skippable joints on Eminem's classics. Rae by far honestly. And it's not fair.
Now Ghostface vs Eminem would be a sick debate. Those two could probably do one crazy album.