Depends on what features you want
I do a lot of machine appliqué as well as quilting, so for me, auto-pivot is a 'must'. Not to have this feature on my machine would be like washing dishes by hand, lol.
That, and the built-in walking foot for straight (as opposed to FMQ) quilting. Therefore, Pfaff all the way! I have the QE4.0 and the Performance 5.