There’s a lot that nobody knows yet, but there are a few things that I personally think strongly favor a PC over the XBox version, depending of course on your style of “play”.
First, if you want VR (and trust me, you want VR), your choice is made. The XBox has no VR capability, and to date anyway, MS has completely shot the idea down. That could change tomorrow, of course, but that’s how it is now.
Next, do you want to play now, or wait until “Summer 2021” arrives, whatever that means. It’s out on PC, but not on XBox.
And then there’s your style. Do you like to goof around and fly around familiar landmarks, possibly using almost exclusively an outside view (i.e. do you use MSFS as a toy/game), or are you a serious simmer, who does realistic Point-A to Point-B flying, using IFR charts and approach plates, completing a flight from start to finish (perhaps even gate/parking to gate/parking? I personally call the toy/game type a “gamer”, and the serious type, well, “serious”. If you’re a gamer, the XBox may be the right choice for you. The costs are less, though it has a lot of disadvantages… No VR (which I already said), very few 3rd party addons available, flying with an XBox controller is no way to fly an aircraft, and much more.
So there are some facts and some opinions on the matter, which certainly didn’t answer your question, but hopefully gave you some good information for you to come up with your own answer. Personally, I’m hard-core simming on a PC all day. In fact, I don’t own a console of any kind anymore, nor do I ever intend to. But that’s me, and you and I are two different people.
Good luck to you, if you have any questions, just toss them at me, but please tag me so I get notified. Merely responding does not do that.