The thread depends on the look that Im going for. I'm making a quilt where I want it to look shinny and then I'm using rayon. I made free standing lace ornaments and emblibrary.com site says that polyester is stronger so I used my serger thread in the large spools. When I made my daughters wall hanging stained glass nativity scene I used mostly rayon but if I didn't have color I'd use my aurifil to fill in the small spaces. It just depends. There are places out there that have great ideas to learn by. Like Viking and emblibrary.com have info on stablizers, etc. Just research and on the emb site look under their projects and you can see how they do them for more ideas.