Exarch vs NPO

I don't know much about Killteam, and I just wanted your thoughts.

I am going to play in a narrative campaign against NPOs, so joint-missions only.
I am playing Blades of Khaine. I can pick one of three Exarchs; Dire Avenger, Howling Banshee and Striking Scorpions.
No matter what model is used the statline for the NPO is always the same.

Which Exarch would perform better against the NPOs? Is there a real difference, or it is more playstyle? I mean, in 40k, if I faced Marines, the Banshees would perform better, but against Orks it would be Scorpions, and so on. So against the NPOs, which is the better, or balanced choice?