Welcome from South Louisiana. I don't have either of the machines so have no advice for you. Some of the newer machines have an even feed foot that seems to be very helpful with piecing. I was considering a Pfaff for awhile, just because of that function, but then I realized I did not want to learn a new machine so stuck to the ones I already had.
I almost bought a Janome a few years ago and neither the saleslady or I could figure out how to work the almost automatic threading device. I ended up with a Brother because it would thread the needle itself. As I have gotten older, I have appreciated that function more and more.
The good thing about the Bernina is that the feet and bobbins you already have will probably be interchangeable. I would check that out.