I liked the aerosoft one in P3D and the JarDesign one in X-Plane.
For p3d Fslab for sure, more detailed and pro than the others
And for X plane, Flight factor is perfect and for the a319 I recommend Toliss
FSLabs is the best and can't even be compared to any others.
As people stated, A to B, Aerosoft is good enough. For much more immersion, FSLabs is the real deal
my vote is (obviously) the flight factor ultimate a320
If only FSL has sharklet variant. I would go there
if you have xp11 the best is the ffa320
for p3d I prefer Aerosoft, it gives me good frames and has all a318 to a321
For X-plane FF all the way