The reason these three artists are the best of the 2013, is because given the scale they operate on they're the only one's to put out album's that mattered. I'll continue on to prove my point.
John Mayer is the most talented popular musician of this era. Let's call this era "iPhone5MileyCyrus" for short. In the entirety of
iphone5mileysyrus nobody else is offering up a good album. There's JT, and he could be the next Michael Jackson, but he's not, and Radiohead hasn't put an album out in two years so there you go. At the peak of Mayer's skill he put out an album that challenged music to be real and authentic, slow release, and good.
Kanye is the last standing icon in Hip Hop in the iphone5mileycyrus era. All those indie guys suck, everyone in the underground is garbage. Jay Z is insane, and old, and his flows are yucky. Kendrick is a cool kid, but he doesn't bring anything new. A big ego is not new. Mac Miller, is too high to be relevant. Drake is just.. Drake. That's that. At the peak of his career and life accomplishments West put out an album that challenged Hip Hop to push boundaries further, and be even more provocative. He could come down to earth with his next album or go further off into space, either would be cool.
Kings of Leon is the only rock band. Arcade Fire could probably churn out a good record though. Kings of Leon proved that selling out isn't the end, it's the beginning. Now they have the spotlight and they made an album as brilliantly calm and human as Mechanical Bull is. I saw them at Coachella in 2012, and the air was buzzing, because all the indie kids were mad that the band they took for granted became popular and made songs for everybody. Well now that they have become the language with which popular rock speaks, they've proven it was worth it by making music that is as honest as it is well-roundedly rock and roll. (The end of this paragraph got away from me, but you get it)
What about the other genres. There's classical, but they could stop making new classical and no one would really notice. Classical music used to have rebels now it has none. Jazz used to have technique professors now it has none. Dance music is not music, it's a soundtrack, nobody has put out a dance album that I would consider a real album of music. Indie gave us Lorde in the iphone5mileycyrus, and she makes music for television show soundtracks, thats cool but what about music. Keep in mind I'm talking about those with high levels of popularity.
So what am I saying? Learn from these guys and judge the rest.