On my machines, I've used the following:
1. 1/4 seam stitch, with my edge foot. Makes piecing a breeze.
2. Alphabet stitches with the memory. I use it to label the backing of my quilts.
3. Needle up/down. Good for piecing multiple items sewn one after another.
4. Walking foot and guide. For SID quilting.
5. Bobbin winder.
6. Satin stitch. Great for fixing holes in sheets, etc. from the dog's nails.
7. Thread cutter.
8. Automatic button hole foot. Creates the perfect size button hole, based on the button.
9. If I ever do any fused applique or crazy quilting, I'll try out some of the decorative stitches. Still on my to do list.