A lot of the trade mags are mostly ads. Which isn't always bad as sometimes you need to see what is for sale too
A few that I find have worthwhile info:
Outdoor Photographer
Digital SLR Photography
Digital Photo Pro
ct Digital Photography -- This one is my favorite, not cheap but when they do an article they do an article not a couple pages of mush that doesn't really tell you anything. Not a lot of articles per issue but very in depth.
I have moved all magazines to digital using Zinio, if you don't mind reading them on screen it is a lot cheaper.