The best Darktide Skitarii build for my money is all about the powerful Chordclaw ability. While the Servo Skulls are certainly fun and provide a lot of utility, such as rezzing allies or solving puzzles, if you're a melee-enjoyer like me, Chordclaw's skewering hand is too good to pass up, and can brutalize both bosses and tanky enemies.
I'll explain the build in depth below, but it's essentially about crit-ing lots for added bonuses like regaining ability energy, and then using Chordclaw lots to murder enemies and gain further bonuses. It's pretty straightforward, so here's how to set it all up.