Of course, much depends on how you define "house organ" magazines. Magazines with games in them--are they house organs? I suppose so. So both STRATEGY AND TACTICS and MOVES magazine were "house organs." FIRE AND MOVEMENT (before DG got it) was not. Once DG got it, it is. I guess.
Okay, my favorite CURRENT "house organ" magazine is AGAINST THE ODDS, followed by MMP's OPERATIONS. I read ATO cover to cover, to include the game rules, when I get it in the mail. I read nearly all of OPERATIONS when I get it in the mail as well. S&T, F&M, and others...I'll confess, I don't read cover to cover.
My favorite OLD "House Organ" magazine was--probably for purely nostalgic reasons--The Avalon Hill GENERAL magazine. I don't need to explain it. Those that agree understand why, those that don't never will, and I don't begrudge them.
Least favorite house organs. I can't remember the name of the magazine, but Terry Shrum of Fresno Gaming Associates put out a mag that was much like their games--graphically slick but pretty much devoid of meaningful content. Sigh. I think there was only two to three issues...