I'm about 2s off that pace. Last night I tried it out a bit but also tried NetKar pro, rFactor2 and iRacing. I reduced the FFB strength on AC and the feel was much better. I think that I'd place AC just behind rFactor2 and ahead of iRacing. After trying NetKar pro, I'm not sure that I wouldn't put it first. It felt really, really good. LFS would be in the mix with all of them but I haven't tried it in a while. Some thoughts:
iRacing: I don't really get a sense of oversteer through the ffb or sound of tires. I don't get a great sense of slip angle. The advantage that ffb reacts to small fluctuations on the road like you would feel in a real car. This might be do to more detailed tracks. Maybe a little hard to prevent a spin. I'm not sure if that is a tire model issue or because you can't sense the slip angle until it is too late.
AC: Not sure what to say specifically. Everything just feels a little better than iRacing (except track detail). A little more sense of slip angle, and little more sense of understeer through ffb. Easier to prevent spins. Just feels really good.
rFactor2: this just clicks for me. I like the tire sounds, really informative. ffb through understeer isn't any better than AC maybe a little less but with the tire sounds and visual sense of slip angle, I really feel like I can control the throttle to keep the car at the proper slip angle.
NetKar pro: just did a few laps in this but wow. It was really good. The best sense of oversteer through ffb out of any sim. You could feel the car skip across the surface in a slide. My only thought was that the formula car that I tested was a little more biased towards understeer than what I would think. Not sure if it had lift off oversteer or not. But it sure did feel good.
LFS: it's been a while since I've played this but from what I remember, LFS didn't give you a great sense of oversteer through ffb. What it was really really good at was giving you a good sense of slip angle visually so you could control it with the throttle.
pCARS: Depending on the build and car, a significant step down from all of the above but it is pre-alpha and fluctuates a lot. It does give feedback with oversteer through ffb but it seems a little exaggerated. pCars is developing everything at once (graphics, content, physics) with maybe more emphasis on graphics while rFactor2 went with physics first.
This is mostly just about feel. There are a lot of other physics features that are different throughout the games. For example, in LFS and rFactor2 you can flat spot the tires, while in iRacing you can't (not sure of the others). rFactor has track rubber in and weather. AC won't have weather till future releases. NetKar pro has weather. It also has thunder and lightning which is pretty cool though I think they'd stop any race in a thunder storm.
After reading all this, please realize that I probably don't know what the hell I'm talking about.