It will depend on player setting/farming area.
High level guide line would be:
Lower player settings : shako
Higher player settings: Nightwing
Middle ground is shako + facet
Shako quality of life is just too good, and kill speed only changes significantly at higher player settings. Also if HC, shako
So if running for exp, Nightwing
If mf, shako
Just my 2 cents
Also if running for style, nightwing