For me R3E is the best sim out there.And thats because of its scalability.You can run some pretty good races at Get Real or you can relax and enjoy a few laps on Amateur or Novice without the anxiety for mistakes.Neither AC nor PCars can do that.Also full series (DTM,WTCC,ADAC and more still to come) is another plus for my personal taste.Just my 2 cents.
I get the best from using both AC and R3E. AC has better physics, driving, car graphics, R3E has better sounds, AI, environment graphics and also a pleasant feeling to drive. For hotlapping and simply cruising/driving, I use AC, for racing the AI in satisfactory and often dramatic pack dogfights, I use R3E. Laserscanned tracks only make a difference when you can compare them to the real thing by experience, or to not laserscanned pendant tracks in other titles: the Nürburgring in AC and in R3E for example drive quite differently, AC's version is more complex in surface, elevations, camber and stuff like that. Currently, R3E offers imo the better general, overall package: more famous tracks and way better AI slightly beat better physics, because the driving model in R3E also is not a bad one. Taken for itself , it really is very good and pleasant. AC scores for its modding community and way more customer friendly pricing model: R3E should cost more than other racing games, because I believe in that better stuff should cost m ore for sure, but the way it is now, it is too overpriced when considering all content there is. Kunos and AC on the othe rhand sell themselves under price. Maybe they are philantropists. Or they simply can afford to work not for money, but fun. I am really curious to see S3's laserscanned Nordschleife and compare it to the one in AC.
AC license their engine to automotive and racing companies also, so they can get more money that way.
Some improvements and new sound features should be part of the next update and I'll be happy to give some details about it soon, so stay tuned