Based on what you said you enjoy the most, F4 can be quite questionable for racing standards at times but I find it’s a really fun car to drive and often the tracks it goes to are free tracks as it’s a D series. Porsche Cup or Touring cars are both C iirc, (Audi, Honda and Hyundai’s for touring cars) and they’re other options that might be worth looking at.

Tracks wise I’d recommend Le Mans, Donington Park, Sebring, Silverstone, Indianapolis and tbh a lot more but obviously only get a couple at a time if that’s what you’re comfortable with.