Two articles in the April issue of the Magazine seem best for medium stakes players.
Nate Meyvis' article is a spead-limit article. But, the ideas in the article should be applicable in both no-limit and pot-limit.
An Overlooked Under Representation
I suspect David Sklansky's article could create quite a bit of debate. I'm sure many players would play the hand he describes differently than he suggests.
It Doesn't Always Depend