It depends on how the hair was made. Strand hair requires different settings,, just like transmapped hair.
Some say Ali hair is great, I say Biscuits hair is great, others swear by OOT's hair is great.
I get good results with all of them - just adjust your specular, roughness and IOR settings. Play with it, they may be different for every scene.
Results like in the image are fine for me.
There is no general setting.
Configuration: Windows 10 64bit Creators Edition, I7 6850K, 128GB, 2 GeForce 1080ti, P11 Pro SR6