On the older Pfaff I love the IDT (walking foot), needle up/down, change in needle position, the low bobbin indicator, and the stitch-in-the-ditch foot.
On the BabyLock I love the tie off feature, needle up/down, huge display, awesome stitches (cleaner stitch than the Pfaff), drop-in bobbin, separate bobbin winding motor. Thread cutter is nice but I still use scissors a lot.