I love the way both games drive, especially now that I've found FFB settings, in conjunction with the Jack Spade tweaker files for Project Cars that bring it closer to AC FFB, that was a win and what a revelation!
In terms of ease of use Project Cars wins hand down though. I have nothing but trouble getting AC up and running, when I was running triple screens and especially in VR, although it's better now than it was. I lose my controller config all the time, on triples the screen bounces around before deciding which screen to appear on (not always the same one). I don't know, in some ways it still feels like a Beta to me. Project Cars just works each and every time I switch it on...and VR was there as native support, it just worked. I don't get enough game time to faff around with AC, which is why I end up playing PCars.