Spike Jonze is the man.
Drake is the future, his lyrics are crazy.
Kanye is the best producer out there in terms of quality and consistency, and he also has nice lyrics too. But I think he's bored with the game, and really wants to do something else. His last album moved into the "I'm so bored, I just want to do something really off-the-wall to see if I can make people like it" territory.
Jay-Z is like the Sinatra of rap to me (a legend, consistently quality material, trailblazer in terms of what a mere "rapper" can be), but he'll always be in the shadow of Notorious B.I.G. in my eyes. Biggie could do any style and make it both believable and entertaining. Jay-Z is top-tier but doesn't quite have the charisma of Biggie. He's more business, less gutter. He's more notable for his longetivity than anything else, which is undoubtedly remarkable. He's never had a bad album, either.
Eminem can destroy anybody lyrically. I think, like Kanye, he's so good that he's bored. Nobody comes after him any more because they know he'll wipe them off the map. Take a listen to his diss track aimed at Mariah and Nick Cannon (especially Nick Cannon, my word Em tears that boy apart) if you don't believe me.
Mos Def is also a lyrical genius. His musical choices leave a lot to be desired (I would say the same thing about Nas, that guy has some of the best lyrics but worst beats on his albums), but listen to stuff like "Mathematics" and "Champion's Requiem" and you can't deny he's one of the best out there.
Nas killed it with Illmatic - arguably my favorite album ever - but everything since then has been mediocre to terrible. He's the classic guy that has three killer tracks on each album and then 15 other tracks that are straight garbage.
I've always been a fan of the Wu. Liquid Swords, that's all I really have to say. I really want to check out Only Built for Cuban Linx 2, as well. Triumph is also sick, and you know, 36 Chambers.
I'm not a Lil' Wayne fan. I don't hate the guy but I've never seen what qualifies him as "The Best Rapper Alive". Everybody raves about how he doesn't write raps and freestyles everything, but my problem is that you can TELL he's dropping stuff off the dome. It's impressive, but some of his raps are terrible. His raps SOUND like freestyles. Jay-Z doesn't write anything either (neither did Biggie), and you can't even tell. I still don't believe it, but watch Fade to Black and Mike D. from the Beastie Boys is there with his jaw on the floor, raving to Rick Rubin that Jay doesn't write anything and just goes in the booth and drops it. He couldn't believe it.
Yeah, I listen to a little rap.