Hello there, like the comments above different rules apply for different races and these alter each year so there is no perfect style/format to use, these guys race and its all about winning, TC is used in many forms of motorsport but to control tire where aswel as create grip. I'm sure many drivers out there will produce faster lap times with it off but there tires will not last the time.
I feel that the best settings are old skool, you want the settings that allow the driver to control as mush as possible himself, then there is more to judge him buy and he is deffinatly working harder, no TC, no ASM, no Automatic, and clutch with gears not paddles if you can
there is two videos on youtube which show this, one in the NUR lap in a GTR and the other is a NUR lap in the ZR1
Personally driver wise im alot more impressed with the skill from the guy in the ZR1 just because you no he is keeping that car on the road and not the fancy system, Im not saying the GTR is a bad car by the way all you GTR lovers it is EPIC but if you wanna see who the real drivers are I'd send them out in ZR1's lol