http://warthunder.com/Think World of Tanks but with planes (I haven't actually played World of Tanks but I've heard that it's a similar model). I guess it might end up as pay-to-win but from what I've seen so far it's pretty excellent. It also doesn't need an "exxxtreeeme rig" to run with most of the pretties turned on. I'm not sure what my PC spec is but it only has one LED and it runs really well, looks gorgeous in fact.
It's by Gaijin, the same people what done Birds Of Steel and looks pretty similar, it even works well enough with keyboard and mouse. Anyway it's still in Beta but I applied and got an invite pretty quickly.