I think Emimen is almost like the Elvis of rap, very talented but has gotten big way more off his image than talent. People have their different opinions of who would make a top 10, and for that reason I think it's insulting to all that came before him to say that Eminem HAS to be in the top 10, because he doesnt deserve that guarantee based off skill, lyricism (seriously making eric cartman impressions and fart jokes, when he's not talking about ******/killing people, puts you in the top 10?!), and relevance, because he was for a few years but is hardly anymore IMO.
He's obviously very skilled but there have been A LOT of skilled emcees and the only ones that should definitely get a spot in a so called top 10 would be Rakim, KRS, Nas, possibly Biggie and/or Pac and possibly Jay-Z (love him or hate him, his longevity makes all that came before him seem like a joke, and his influence is undeniable). I would also probably throw Kool G Rap and Big Daddy Kane in there, not to have a bias towards the late 80s originators, but I feel their skill level is STILL rarely matched. I would also venture to add guys like Gift of Gab, MF Doom, Mos Def, Pharoahe Monch, Black Thought and Q-Tip into the discussion, but it may just be that they're some of my personal favorites and I love their styles.
Boofy!: Check out Chiddy Bang, they're legitimately talented but make some of the catchiest, pop/party-friendly rap I've ever heard.