Hard to tell really since they're not really synced. Out of all the Nordschliefe's I've experienced, Gran Turismo still sets the standard. I'm keen to try AC's, Forza is again way too wide.
As jono said. Hard to say as they seem to all be at different times of day. Raceroom's seems to be the worst IMO. The other three all look good. One better than the others at certain points, then worse at others. iRacing probably the best maybe.
Yeah I think IRacing seems to be looks better than the others but it would be good to see them all at the same time of day.