Only payware would be even slightly reliable, the feel and sensation are completely off obviously becayse you cant remotely simulate that without a full motion simulator.
You can edit CFG files to get the correct fuel usage and stuff aswell.
You cant have your cake and eat it... What the hells the point in having it then!!!
Crud in = Crud out
It's the same with both sims. A badly designed plane will not fly accurately in either sim. What I think can be made more accurate in MSFS is aircraft systems. PMDG are the prime example of that.
The rest is up to the datatables to make the plane fly correctly.
Xplane has an aerodynamic engine that allows anything to attempt to fly. Build it in Planemaker and test it out. I'm more into making real aircraft fly by the manuals and the tables in them.