I piece with a size 70/11 using either topstitch, microtx or quilting needle and either Aurifil 50 wt or Superior Threads Bottom Line (60wt). When I switched to the finer threads and thinner needles That improved my ability to get a scant quarter inch seam.
When quilting I use either a topstitch 90/14 or 100/16 (even if I’m using 100wt thread) or sometimes an Organ anti-glue 75/11. Those types and sizes just seem to work best for all my machines when Fmq.
Rob