Mary568,
I have used Sulky in the past due to the prices I could find at Joanns when on sale. However I am a huge fan and do own Floriani thread. The sheen is smooth and I do not have any breakage when embroidering. Sometimes my machine is testy when it comes to certain threads but I found that Floriani for me is the best as well as their stabilizers. You will find many of us here have at one point used different brands and would prefer one over the other. I have used Madeira in the past but for some reason my machine doesn't like it (yes my machine has feelings too
). Hope this helps a bit, I"m sure there are many here that have a preference of their own.