Based on last years seniority list for both:
50% RS at JB 2013/10/16 DOH
2013/10/16 DOH at NK 23% RS
50% RS at NK 2017/06/11 DOH

Plenty of people bypass by choice at either. But of the people hired at both in 2013 (according to last years seniority list) 50% are FOs at JB, and 5 out of 250ish are FOs at NK....
And that only makes my point, as a lot of those will take the upgrade with all the NK getting placed below with some mix of RS/DOH. Yes, based on DOH some NK will go above, but for JB in that group RS will improve, they will take the upgrade, and for NK upgrades will stagnate. Not complaining, just the likely outcome. In his spot I would take DL over NK.