It's not a well kept secret that those that complain of bias towards one brand on this forum have biases of their own towards another.
That's pretty much the way I see it. We don't control or regulate the brand preferences of anyone on this forum, and I suspect that the vast majority of participants here actually enjoy a number of different brands--Lionel, MTH, Williams, Weaver, Atlas, 3rd Rail, RMT, and more.
Perhaps there are simply more MTH operators on this forum, for whatever reason, but I kind of doubt that is the case.
Layout features I receive for the magazine display what is pretty much an even distribution of motive power brands (and rolling stock), although I really don't pay much attention to that unless the author elects to mention it in the text or captions, and/or if he or she discusses the control system(s) used.
From the advertising perspective of the magazine, Lionel is certainly one of our major advertisers and you can darn well believe we are grateful for their consistent support.
Product reviews are selected on the basis of what is available (and new to the market), with little regard for who made the item. And "Smoke Signals" listings are available to any firm or supplier willing to supply the image and info.
So, if one brand or the other receives (seemingly) more discussion on the forum, it's likely the result of those who own one brand or the other being more motivated to write about their experiences. It's certainly not an intentional bias because anyone is welcome to write whatever he or she feels so long as the initial and ensuing discussion remains civil.