As someone who reads both PPRuNe and Flyer (and even uses the same name on both), my observation is that both go up and down in quality. The interesting questions and the useful answers have all been done thoroughly, so to the "old hands" they are repeats and boring. To the newbie who isn't adept with the search facility, they are something else. We oldies have to live with that.
Two things have struck me on both forums:
There are folks who don't shout about who they are (or have been), but whose wisdom and aviation knowledge are beyond what most of us could dream of. Yet those folks get insulted by low-houred (or low-brained) self-appointed experts on both forums. Most don't retaliate - they say nothing, or just leave quietly. I had dinner a few weeks ago with a former RAF aerobatic display pilot and a senior training captain for a major airline (not BA). Both had been told they know nothing ... by a PPL stude with an overinflated ego. They'd both also been "corrected" by a qualified but still less than omniscient recent IR. They chose in both cases to remain anonymous, so I will continue to respect that.
There are trolls on both whose sole aim is to drive people away from the forum they have decided to descend upon. I received enough gratuitous insults a few months ago on PPRuNe (not in here, I hasten to add) that I decided to make my visits very rare.