I think I have answered these questions/rants so often I should probably put it as part of my signature
I will speak from my own point of view as a spanish atco but I assume the french do it exactly the same. It's one of those few times where doing it right and choosing the least amount of work is the same
As some other Atco's have pointed there is more or less an optimum way to handle traffics. Obviously there are times when 2 aircraft are in equal position to be nr 1 but this is rather infrecuent. Any other action which is not the optimum is more work for us. Any pilot stating "the atco's from X country are always giving preference to their national carriers" must be prepared to explain why atcos would be willing to take so much extra work.
One atco at the beginning of the thread stated that special treats from a specific airline (which does not have to be the national one) was the tipping point when deciding to be nr 1... not my criterium but it would only account for those few times when 2 aircraft can be the first with equal amount of work.
We are not always perfect. Just the other day I allowed a slow aircraft to depart while a B737 was making push. I thought it would have cleared a certain altitude by the time the other one reached the holding point but I was mistaken. The B737 had to wait for 5 minutes due to that and I had a lot more work due to coordinations. Was I favoring a national carrier? Nope, just screwing things up but without any bias.
On the other side I tend to consider these statements of pilots about giving priority with the same degree of confidence of football fans questioning a referee's decission. It's always the other team the referees are helping.
It's you pilots (sure, not all of you but since we were making such sweeping remarks...) who are obsessed with being nr 1 and who would cheat each other for it without hessitation. I couldn't count how many times I've had pilots saying they are fully ready for push... while the towtruck was not attached and some stairs still on...
I couldn't honestly care less which one is nr 1. Usually it will be a medium before a heavy or whichever SID causes the least havoc when compared to the one before and after... and that's it, I simply have no time checking for the carrier before assigning startup order.
Hmmmm.... perhaps a bit too long for a signature