I have read Blade, Tactical Knives, Knife World, Knives Illustrated.
I had a sub to Blade, I enjoy reading Blade, but think about it. If Blade writes a bad review about a knife, then that knife company or maker will probably not want to advertise with them. Simple economics. If someone decided to send me a free sub to any of the mags listed above, I would pounce on it immediately. I have nothing against any of the magazines, and actually enjoy reading the articles to gain some history on knives, knife steels and to see what's out there. The only reviews I take any stock in are reviews in Blade by Kim Breed, and reviews in Tactical Knives by Dan Schectman. They tell you everything about the knife they are reviewing, and if its a POS, they tell you. To me, they are enjoyable reads, but I've learned so much here in the past year and a half, much more than I could learn reading any of the above magazines. I do have to say that Knife World is unbiased in its reviews to an extent, although I've only read two issues.
For good knife reviews, I read a magazine called Backwoodsman. It's a back to the land, simpler life, off the grid magazine, devoted to hunting, fishing, camping etc. Dan Schectman also writes for this magazine, among others, and the reviews either praise products, or, if they are not up to par, tell you exactly why they aren't.
I really like the layout of Blade, the pictures are great, the writing is upbeat. I just think the reviews aren't always in depth enough.
To add, this is only in reference to knife reviews. These magazines cover steels, different makers etc. I have learned a lot reading these magazines, but I feel I have learned more being a member here.