Independent artists that are staying out of the mainstream fake beef and singing for kids music. Independent and underground artists make the best music... they just don't have the money and advertising to get their music out as big as a 50 Cent or Cam'ron... but as far as music goes, they run the game for consistently putting out the best music.
And out of your list, I would have said Rocafella a few months ago but I am losing respect there, Aftermath would have to be my pick even though I have also been losing respect for the music there. Maybe D-Block? It's all close but not important anyways.