I always use what comes with the machines. I have 2 older kenmores that state in there manuals ( For best stitching results use clear plastic lightweight bobbins when stitching at high speed with widest and longest stitch setting.) To this day I just use the metal ones that also came with them because I am piecing and free motion quilting and don't need the stitch set at the longest stitch setting length. They give me a very good straight stitch. Bobbins are very important in getting good stitch quality.
Suzy