Ok so if no one has answered this already, the real answer is both matter. when i rework cars the hardest part is to get the "physics/ffb/handling" to feel good. force feedback settings can only be adjusted as (ffb strength mult=) where i can add force feedback strength to a car in the physics) or i can adjust the steering ratio so 10:1 compared to 20:1 will feel different. 20:1 feeling like a 1960's loose steering and lower numbers becoming more and more sharp. 1:1 is probably gokart steering. and finally you can adjust the linear rod steering ratio, the lower the number, the less the tires turns. so high numbers in this category make a car a drift car with high angle steering. all of this combines to make steering feel.
so now we come to physics. if you get all the FFB settings perfect, you still have to address the weight of the car and suspension figures. because you absolutely feel that though the steering wheel. so having suspension data that is incorrect can ruin FFB feeling aswell. part of my issue with the Toyota supra time attack car i made, i made all the suspension settings too soft, and even know the force feedback settings were very aggresive like you find in a GT3 car, everyone said the car itself felt like a street car. so both physics and FFB settings on a car are equally important. if you get one wrong it ruins it for both, people will assume both the physics and FFB suck if you get just one wrong. its hard to distinguish between them when driving a car. you'll just know something is off, and delete the car afterward.
that makes life way way way way easier 
