The quality and depth of the writing in Jacobin's stories is what keeps me coming back. They go very in-depth in each story and aren't afraid to use a diction that's probably a bit more academic than the average American is comfortable with. Each piece is exactly as long as it needs to be, and they don't dumb down the content or try to soften their ideological views the way most mainstream publications do.
I especially love that the subject matter is political but not reactionary, taking a longer view of social and economic issues rather than just producing articles focused solely on the outrage of the week. Only the writing in The New Yorker is better.