I subscribe to quite a few publications.  But if I had to choose one, this very well could be it. 
Its put out quarterly.  I know, bummer, right?  I have to wait three months for new articles?
For starters, there's no advertising in the issues.  Which I love. 
The articles are very well written, with plenty of picture examples.  Grant it, there are some articles that don't pertain to the types of pictures I take, ie portraits, but the information is still helpful non the less. 
They also put out a Big Book of Photography, I think once a year that is great too.
You can get back issues, as well as view some previous articles on the website.
http://www.photographic.com/