Thanks for your very informative replies, certainty has made me reconsider my options.
I did actually try the trial version of Xplane a while ago (version 11, I think), but wasn't particularly impressed with it. For me it seemed that the flight model was a little too "bouncy" with the larger airliners. Has anyone else found this? It seemed better suited to smaller aircraft, and as I prefer the larger airliners I decided to give it a miss. Maybe they have improved the flight model since then?
Interestingly, I do have a VR headset, it's just a first generation WMR, and I have used it with FSX using the Flyinside add-on. I have to agree with you John, that VR is a vastly superior experience, but the biggest issues I had was using the controls with the mouse and looking at flight charts. How do you get around these issues? Having physical controls in a cockpit with triple monitors would be easier, although somewhat less immersive than VR. One of my favorite aircraft is the Just Flight DC-10 HD, which is apparently compatible with PD3 versions 4 and 5 (as well as the older 32 bit versions). Flying this in VR with its old-school steam gauges is truly amazing. This reason alone would almost tip the scales toward PD3, and I don't believe that MSFS2020 has a DC-10.
Your comments jcomm about PD3 v5.3 is reassuring. Do you use it with triple monitors?
So it seems that I am favoring PD3 atm, and will seriously look at MSFS once it matures. Once again, thanks for your inputs.