Of recent games, I'd would have to say that IL-2 is pretty much the best I have come across; although I have got a real soft spot for Harrier Jump Jet from Microprose. I spent a ridiculous amount of time on it when I was a kid and would love to see it here on GOG.

I've never been a big fan of flight sims, but I used to love playing F19 Stealth Fighter (Microprose) as a kid. I don't know if I ever completed a mission though.

I've yet to try some of toe true flight sims here (or anywhere!) so I'll have to stick with Freespace 2. Since you included it on the facebook poll, I'll put it in said genre as justification for the choice.
If the X series counts then X3 instead.

I'm old-fashioned. Microsoft Flight Simulator for Windows 95.

MS Flight Simulator 5.1, I used to play it hours on end when I was growing up. I'd plot out flight paths during school.

Well, for me its Microsoft Flight Simulator X. :)

Freespace 2, definitely.

Flight Simulator 2004. Best one by far, even better than X.

Wing Commander 3 easily. . . Boy it sure would be nice to play that on xp and without all the disc swaps :-)

When I younger I used to play a lot of F-15:Strike Eagle II by Microprose. It was actually my first flight sim, and my dad even bought a joystick to play it with.

First there's a non-reward facebook poll, and now this?
he seriously wants us talking about flight sims.

Jane's F-15

I admit my inexperience with flight sims, only one I every really played was F-22 for the Genesis, by all accounts rather mediocre.

I'm not too fond of flight sims but Red Baron was pretty cool.

IL-2 Sturmovik
Although I couldn't finish even one mission I as having fun just flying around and trying to land the plane :D