I've not used either of those games before, which one is the better of the 2 ?
Beatles or Rolling Stones? Labour or Conservative? United or City?
Of course, which sim to use is much more contentious than music, politics or football, as five minutes in any of the FS forums will demonstrate.
FSX is cheaper (and older) but, other than that, it is horses for courses.
There is a new version of Microsoft Flight Simulator out, but don't expect to see aircraft add-ons as complex as Vulcan for a while yet.
This is getting dated but might be worth a look.
https://www.justflight.com/new-to-flight-simulation