I don't believe there is anything obvious about it. I think the way W3 lays out information is likely better for beginners. And MDN is likely better for the av

I don't believe there is anything obvious about it. I think the way W3 lays out information is likely better for beginners. And MDN is likely better for the average professional developer. So the question is who makes the most searches for those subjects. That said, I do actually see MDN as the first result for some searches.