AC is popular, but pCars still more (753k vs 472k "owners" on Steam) and VIR is in Forza 6. Building some fantasy-tracks isn't covering the fact, that to much is missing in AC. And the AI seems horrible at the moment. Was much better some months ago. I switched to AMS for AI-races. Not many cars, but with the evenly good Giranthon-Tracks (try out Le Mas du Clos), the much better AI, the better FFB/grip/fun-feeling in many cars it hooked on me a lot. Having a lot of cars to choose, even most are great and accurately done, don't cover the downsides of this title for me.