It's not the thread colors so much as the type of thread. There are so many now. I find CT threads fuzzy and has slubs in it. I haven't used any in a couple of years so maybe it has improved. I like Wonderfill, Aurifil, Masterpiece, and Guttermann for piecing. I have Signature thread but find it is linty but sews fine. Sulky and YLI are good threads. It doesn't matter what color you piece with unless you are sewing white or pale fabric then I wouldn't use bright or dark color thread. I use 60 wt thread for bobbins.