I'd be for Civilian Aircraft. I can see some pretty cool missions taking place actually with them. Stuff like the Ruskies guarding their border from NATO, while at the same time civilian aircraft fly over.
And for those saying the map is too small, ARMA 2 [With its full non-existant flight models] even had modelers make Civilian aircraft. Yes, you could fly from one side to another in five seconds... But it still helped the simulation aspect a bunch.
I suppose before implementing a full Civilian aircraft, ED should try with a Transport bird first. C-17 would fit fantastically IMO.