A lot has to do with the sewing machine. Some machines are persnickety - others not so much. One of my machines does not like Coats and Clark, the other doesn't mind. Another issue is lint. Polyester threads are not linty at all. Some cotton threads (like Connecting Threads) are quite linty. I generally use cotton thread for everything because I have tons of it. (Bought on sale.) The old rumor is that Polyester thread breaks the fabric but that myth has been debunked. I'd suggest that you try a few different types and see what you and your machine like. Then look out for sales.