I am a magazine junkie; I am a magazine connoisseur. I love to read well-written features on tech or culture or music, if there's substance I'm happy. New Yorker-esque.
New Yorker. The Atlantic. Harpers. Slate and Salon are a rung below that. Wired doesn't always totally suck. I'd mention Pitchfork but there's a lot of hate against them.
Online-only I could only name the ones I read, namely Smashing Magazine and I Love Typography.
http://www.economist.com/ and http://seedmagazine.com/ have great reputations... at least in my book. They have a very high ratio of signal to noise, in my opinion. I often enjoy http://www.physorg.com/, though it's frequently a little over my head... at the same time, I appreciate that they don't pull the punches, so to speak.
I find that the more magazines I have, the less I get out of them, because I'm able to pass over the "huh? meh" articles in favor of articles I know I'm interested in. It's hard to remind myself that I don't already know what's interesting and what isn't. Easy solution: I subscribe to The New Yorker and The Atlantic in dead-tree form and read them cover to cover (except the New Yorker's local stuff, since I'm not in New York.)
I don't understand how someone could consume a dozen magazines a month. I don't have time for more than two (well, plus National Geographic; my Grandmother gives me a subscription every year.) Maybe I read too much in newspapers (like telling time by looking at the second hand of the clock) or on the internet, or maybe I'm just a slow reader.
I really like the New Yorker, especially the comics, but that has already been mentioned. Harvard Business Review (hbr.com) has some well written free articles. Makezine.com has interesting projects to work on.
Online-only I could only name the ones I read, namely Smashing Magazine and I Love Typography.