I'm proud to say I've never worked with an ATCO who was other than impartial when it comes to any sort of airline priority. These days there are so many other factors regarding order of traffic (slot times, aircraft performance, track divergence for 1 minute departure separations, vortex category, needing to free up a particular stand etc etc), that you tend to forget the flag painted on the side of the aircraft!
It's almost always down to the most efficient, fastest flow of traffic.
Don't forget, pilots are only responsible for the performance of one airline - their own - and occasionally forget the other 15 or 20 aircraft wanting to land or depart within a few minutes of themselves. They often aren't aware of the delays happening to everybody else and so often feel that they're being unduly penalised