If your top and bottom threads are a reasonable match, the crossover between them is less visible. I suspect you are being too hard on yourself and are much more critical than others would be. Since I switched to using Thermore batting, however, the density of that batting tends to reduce the problem. Bed sheets tend to accentuate the problem, in my experience. Good thread and good quality quilting needles do help. After I tried titanium needles, I don't think I will ever go back.