From my point of view, the SF series is probably as close as one can get to the "ultimate sim" right now and in the near future. Why?
Well, for starters, no two persons want the exact same thing from a sim. If person A wants a super-hifi F-8 over 'nam sim and one is made, then person B will bitch because he wanted to fly the A-6 or Mig-21. With SF, you can modify it endlessly to satisfy your own personal taste. It completely owns other sims like MSFS and X-Plane in this regard:
You do not have to stop at merely building a custom plane; you can take your custom plane, make custom weapons for it and place it in a custom campaign with custom forces on a custom map and take part in an entire custom conflict, provided you have the patience to do so. Me? I'm creating my own near-future world for the game, a world where polar icecaps have melted and I can fly SEAD missions searching out missile boats hiding in a half-sunken downtown LA. Why? Because I can, and because I find it to be fun.
So bottom line is that you should all be happy you can tweak this product to your hearts content and have something that's pretty realistic, provided you have the necessary suspension of disbelief. You'll never get that 100% realistic sim, for the simple reason that you can't have 100% realistic flying without actually flying.