I have a Pfaff 7570 that fmq's beautifully and a Singer Slant 403A.
Because I love my Pfaff and it's difficult to get parts for it (these are no longer made in Germany - Pfaff sold out) I just purchased from Ebay the Singer 403A as a backup. The Singer runs like a top and has a little larger harp than my Pfaff 7570. The Singer also does beautiful FMQ so I will use it for quilting, taking some of the workload off my Pfaff.