Microsoft are alright if you want to become an old man overnight and stink of urine. But I would honestly recommend Pacific fighters or Forgotten Battles, these are the last flight sims released from ubisoft and are part of the IL2 series of flight sims.
If you like flying WWII aircraft these sims are about as realistic as they come, with an absolute passion for trying to recreate the original cockpits, engines and flight physics of the WWII aircraft. Even to the point of allowing you to stick your head out to the side of the cockpit to see you finals when landing on a carrier.
The most fun I ever had online was in this sim, when 12 of us online took on 12 online Russian pilots in a dogfight, my heart was pounding for hours afterwards. I did not get shot down, I do not think I shot anyone else down, but everyone said I was great in the dogfight. All too fast and furious but one hell of a rush.