Well I'm thinking of this in terms of decades:
80s
90s
00s
teens
The 90s is going to be fucking stacked. Easily the golden age. The teens is going to be the weakest by far. Timbaland probably makes the bracket if its straight 64 but I don't think he cracks the 90s top 16.
Pac
Biggie
Outkast (could put them in 00s for balance though)
Dre
Ice Cube
Goodie Mobb
Bushwick Bill
Jadakiss
Warren G
Too Short
Wu collectively, plus Method Man, and ODB individually
Redman
Juvy
E40
Mace
Mobb Deep
Tribe Called Quest
Naughty By Nature
and while not my tastes you have to add Puff Daddy, Master P and Salt N Pepa as well.
All those are probably ahead of Timbaland in the 90s line, IMO and that's just off the top of my head so I'm sure I'm overlooking a few people. I'd argue for 8 Ball and MJG too though they straddle the 90s 00 line as well. Tim might fair better in the 00s.
Stacked era.
The teens will still have Kendrick, and even though old fogies might not be Kendrick fans he's one of if not the best rapper in the game right now. Everything he touches turns to fire. He's a genius. It seems like every album is better than the last. m.A.A.d city was considered one of the best albums of the decade, then he dropped Pimp a Butterfly, then he dropped DAMN.
Migos hasn't really been around with that level of popularity for as long, since Culture was really what propelled them into superstardom, even though YRN did gain a lot of popularity. They really didn't get anything until Versace in 2013, then Look at my Dab got them popular right as Culture came out.
J Cole is interesting because 2014 Forest Hills Drive was really good (double plat with no features) but KOD and Eyez Only were much less acclaimed by fans (although popular). KOD is better than Eyez Only in terms of Twitterscape reception, with ATM and Kevin's Heart being general favorites. He has his own very distinct style when it comes to beats and lyricism. Friday Night Lights was a really fucking good mixtape.
Drake is obviously super popular, and he's interesting because I personally kind of liked most of his music but wasn't crazy about it, but as I listed more it gets better. God's Plan is super popular right now. It seems like every single he releases is its own distinct hit.
Kanye is Kanye. Twisted Fantasy (possible album of the decade), Throne, Yeezus, and Pablo all since 2010. Super controversial but all time best seller.
Chance the Rapper is super popular but for whatever reason I'm not really into a lot of his music. I'm so fucking white.
If you count Frank Ocean he's had two super highly acclaimed albums recently with channel ORANGE and blonde.
Post Malone is super popular right now and outside of Logic and Eminem is easily the best white Hip Hop guy. beerbongs and bentleys was fucking great. Lots of hits.
DJ Khaled has been successful but fuck that guy, he just dickrides more talented acts with his beats.
Macklemore is trash but white people.
Childish Gambino is really fucking good. This is America just came out but just shows what he can do as an artist.
Rae Srummurd's album just came out but he makes good music. Powerglide is great despite being overplayed, then there are songs like Black Beatle.
Lil Uzi is really new to the game, but has already dropped several bangers, even though his last song was shit. Tour Llif3 was really good.
Earl Sweatshirt is a guy that I haven't listened to but my friends swear he is super talented. Same goes with Logic.
NF has talent but Christian rap doesn't really count. The white boy in me loves his music.
Future is another really good one. I love his shit.
If you're into the more comedic genre Lil Dicky is really really talented but fucks around a lot. Freaky Friday with Chris Brown was really good shit.
My friends all hate Kodak but he is talented, even if his music is trash.
Cardi B and Nicki Minaj fucking suck. So does Iggy Azalea.
I probably forgot some but that's what the teens has.