X3 is a fun game, with a very developed universe (you’ll see factions conduct invasion in real-time as you do your own thing) with a wide variety of gameplay. The universe of X3 honestly makes Star Citizen seems like a theme park for children.
That being said it is extremely difficult to get into them both because there are so many gameplay options and the UI/UX is subpar (prepare to be constantly fiddling with menu and looking up how to execute a given course of action).
I am engine developer, but even to this day you can clearly see Cryengine 3.x issue in star citizen.
They simulate zero-g areas as a Cryengine underwater map. You routinely see stuff floating as if in water even on planets with gravity.
You can also witness strange bugs that confirm the size issue (that they made everything extremely small in a Frankenstein version of a Cryengine map); one example would be your footmarks suddenly becoming massive.
The completely fucked up physics in sc (e.g. tanks bouncing like beachballs) is also a legacy of Cryengine 3.0.