X-Plane is a great sim, but it lacks several features that helped to make Microsoft's sim so immersive and popular. X-Plane 10 is rumored to add AI traffic so you won't feel like you're flying in post-apocalyptic airspace, but it'll still be a while before the XP dev community comes close to that of MSFS.

Also, I know "FAA certification" is an oft-touted feature of XP, but it's not certified as a simulator, only as a "flight training device" and at the level it's certified the bar is pretty low.

If you're looking to get sim time for an instrument rating, it's helpful but it's not as impressive as it sounds. XP's certification level is more about, "if the joystick is unplugged, pause the sim" than accurate aerodynamic modeling or flight model completeness.