I think it has less to do with SONAR than Windows. I bet 85%+ of the posts in those forums will be from Mac users. There remains intense snobbery around the Mac and music. As someone who uses both Mac and Windows, the only remaining place where I see the Mac having an advantage is the way the OS handles audio. Core Audio is a thing of beauty compared to what Microsoft has done in the past. Also for really heavy-duty, industrial-strength audio/video users, the support for Thunderbolt may be important.
However, there's still no doubt that you get better performance for less money with Windows. Furthermore, "tablets" like the Surface Pro are way ahead of the iPad Pro, which disappointingly does not run OS X. I'd also take a Surface Pro over an Air these days.
However, what everyone at Gearslutz knows that we're too stupid to know is that you can make
much better music if you pay a premium price for really great industrial design.