It's hard to prove any kind of popularity, but if you went by Netflix ratings, DS9 is one of the highest rated of the Trek series, although only marginally. Generally all the series are rated the same there, even Enterprise. While that doesn't really indicate a rise in popularity, it may show that there isn't such a large disparity that people think exists.
TNG still does very well in rerun syndication. I think it is the only Trek still being rerun right now in America. Was it on SyFy?
TNG reruns were even beating new episodes of Stargate Universe in the ratings!