I noticed that this is the first time since the release of Project Cars that Assetto Corsa has had more players than pCars on Steam. That may just be down to the update bringing players on, but you never know.
Really like both AC & pCars but cannot see the physics as any better or worse for that matter, just bit different. But everyone has a personal preference to how their race sim feels. I enjoy them equally and really like that I can go to the other when I get enough of one.