Well, if I'm going to comment on various manga magazines, I might as well comment on the ones I buy for a specific reason outside of just snagging the freebies.
Big Comic, issue 5, 300 yen, 370 pages, bi-monthly (the 10th and 25th of each month). (The 3.10.11 issue.) No freebies.
Big Comic is aimed at an adult male audience, and is best identified by the caricature of a popular media personality on the cover. Often, this is someone covered in the regular media for some reason (such as when promoting an upcoming movie), but it's unlikely that there'd be anything like an interview or cover story within the magazine itself. The stories include SF, adventure, mysteries, drama, cooking and salaryman slice-of-life. In this particular issue, there are a few big names that should be recognizable for one reason or another. The top one is Takao Saito, with Golgo 13. We also have Fujihiko Hosono (creator of Gallery Fake) weighing in with his "Double Face". Then there's Kaiji Kawaguchi ("The Silent Service", "Zipang" and "A Spirit of the Sun") running "Hyouma no Hata" ("Hyouma's Flag"). Finally, the reason I bought this issue, and 3 names that may be familiar to those that read my blog a couple of weeks ago - Masaru Satou, Junji Itou and Takashi Nagasaki, who have created "Yuukoku no Rasputin" ("Patriotic Rasputin").
In general, the stories in Big Comic have a masculine feel, focusing on heroes in one form or another that face rough odds and overcome them. The artwork tends to have heavier, darker lines, and the character designs more stylized. There's a blurring of boundaries regarding whether the protagonist has to be a good guy or bad, as in Golgo, or if the protagonist's opponent has to be the polar opposite, as with Hyouma. As mentioned above, I picked up this issue specifically to see where the story was in Rasputin. This isn't a regular purchase for me, and I may not get another copy for a while.