I’ve held off GT Sport because whilst there may be a good volume of offline content (I personally didn’t think there was), it’s all very shallow and superficial. There’s no progression, or career or anything, it’s overwhelmingly ‘bite-sized’ challenges rather than anything else. It seems they’ve massively invested in the online side of things, which is fair enough. No damage either, which annoys me.
Project Cars 2 is getting good press, but a lot of reviews say it’s buggy and not really out of beta, although I understand there was a patch on Friday which fixed loads of stuff (and broke others).
F1 2016 is very good indeed, and F1 2017 gets a good write up, although I’ve not tried it. It’s obviously very sim heavy though, and lacks the variety of GTS/PC2/Forza etc.
I’ve always enjoyed the Dirt games, again, Dirt 4 gets a great write up. Dirt Rally was tough, but really rewarding when you got it right.