The most realistic flight sim I ever played - dating way back to around 1991 and good old MS DOS... Megafortress. A modified B-52 based on Dale Brown's famous novel.
You had to do everything manually, controlling the piloting, navigating, weapons and defensive stations as you fly over Baghdad. That game had me hooked for months. Learning every weapon, avoiding enemy radar, flying long hours and returning to base safely, even while half the plane was shot to bits and engines on fire. I long for those adventures of pure glory.
As for today's easy "arcade" style flying games? Meh...