I usually hand quilt. My stitch length depends on the thickness of the batting. I like 1/8" to 1/4" stitches. I've seen gorgeous hand quilted quilts with teeny tiny stitches. That's out of my league! I quilt for my pleasure, not competition. When I first started quilting, my stitches were all weird. Over time, I found a stitching "rhythm" that was comfortable for me. With machine quilting on my home sewing machine, I like the number 3 stitch length...whatever that length is on my machine.
I think quilting is a personal endeavor and whatever you do and like, is the perfect stitch length.