Thanks for all the input. Have been testing different needles, thread and tension combinations to see what my machine likes. I have a 20+ year-old Kenmore right now. So far it seems to like the polyester the best. Both top and bottom stitches seem more consistent. Who would have ever thought I'd be studying stitches under a magnifying glass! Thought I'd get a spool of a few different kinds, both poly and cotton and see what happens. The best thing I'm learning so far is that it doesn't seem to matter much. Just do what you like, which suits me just fine. I've always tended to be a rule breaker anyway! Thanks for all the brand suggestions.