Not to stir the pot, but I have an opinion!
I've tried almost all the racing sims, all have their good and bad, and it depends on what you like, personally, I think GT3 cars are boring, not to say they aren't excellent machines, they are, I just get no enjoyment from them.
I personally think the orig Assetto Corsa is still the king of content, the modding scene for that Sim, while slowing down has produced almost every car and track imaginable, all for (mostly) free, you can drive any car, anywhere just about.
In terms of tyre model, I still think Live For Speed is the closest to real life
Iracing, I see how it's good, rating system and all, but I tell you this, I own a MX5 (Miata), it's manual, and within 5 mins of driving it in Iracing, I noped out, I was shifting gears in a spirited manner (yes I have Fanatec pedals and a clutch, and was using the clutch), Iracing kept making gear crunch noises because I was trying to shift "too fast", and like I said, I own and drive that car, you
can shift it that fast, might be a small whine, but I thought, I'm not paying X a month to drive this, if it's as unrealistic as that.
Just my opinion!
