That's a hard one, what feels good to one may not to the next. Much is based on the expectations or focus of the gamer (sim to arcade,online, offline, street/hyper/race cars, etc.). As an example, some loved netKar Pro, I didn't at all but I am not one that wants to invest hours to get a car setup correctly. Out of the box, touch the brakes/accelerator in that one and go for a loop.
I liked the older Simbin titles, LFS, Grand Prix Legends, Sports Car GT, Papyrus Nascar/Indy/Cart, and most of the current. I am not a stickler for utmost accuracy, I want something I can pick up and race without the controls or physics interfering with the experience. I need better than average AI, graphics, sounds, career, and leaderboard competitions, may dabble in online competition but because I don't spend a lot of time in any one racing sim I am not always comfortable.
To me, DTM Experience has a better than average sense of speed, graphics, AI (so far), presentation, physics (feels convincing) and outstanding sounds (best of any in my opinion). Hard to directly compare to pCARS or AC as each has a different but similar in many "sim" related ways. Each has their strengths and weaknesses but nothing that is a deal breaker.