This category is really hard. These are all good magazines.
Apex: Edited by Lynne M. Thomas, Apex features dark fantasy, weird, and horror. The issue included in the packet was #39, August 2012, which features stories by Marie Brennan, Kat Howard, Genevieve Valentine, and Nir Yaniv, as well as an essay by Jim Hines. The stories were all quite good, though I'm not much of a dark/horror reading person.
Beneath Ceaseless Skies: Edited by Scott Andrews and Kate Marshall, BCS focuses on fantasy. The four stories in the submitted issue, #100, July 26, 2012, were mostly good. I especially liked Christie Yant's "The Three Feats of Agani," though I thought Garth Upshaw's "Ratcatcher" dragged on way too long.
Clarkesworld: Edited by Neil Clarke, Clarkesworld tends to focus on realistic or semi-plausible SF without getting into Analog territory. The submitted issue is #64. There's another one by Aliette de Bodard that seems to be set in her larger Dai Viet world, a story in which a roach is engineered to help people, and a delightful piece by Gwendolyn Clare about an octopedal starfish-like alien who encounters humans seeking the Brights, who left a starship for them to find.
Lightspeed: Edited by John Joseph Adams, Lightspeed publishes both SF and F. The submitted issue, #20, January 2012, is the first issue published after the merger of Lightspeed and Fantasy. It is largely reprints, maybe about 50%, including the Anne McCaffrey tribute. Adams continues to find a good selection of stories that are different enough to not be repetitive.
Strange Horizons: Edited by a lot of people, including editor-in-chief Niall Harrison, SH publishes a lot of fiction in the strange/interstitial mode, and well-done non-fiction. The submitted material was the entirety of July 2012. (They publish three times a week, 2 fiction, 2-3 poems, and many reviews.) The fiction was invariably good, and I'm not biased because they chose to reprint Ellen Kushner's excellent "The Death of the Duke" that month, not at all.
This category is going to be incredibly hard for me to rank, because I can't rank three of them 1st.