Funny enough the favourite flight "game" is a ww2 warbird simulator game which is quite dated in today's standard. Its called Il2 and it is fairly simple in comparision to fsx. Well, they are different and difficult to compare as they represent in different era of flight, so I say fsx as so far I have played so far.
Xplane is much better FSX and P3D combined in terms of graphics.
For a long-term user of P3D or FSX, it is very difficult to get adjusted to the settings of XPlane and also with the camera settings.
Also not much addons are compatible with the Xplane