I wouldn't call myself a purist but for fabric I only use cotton and mostly Moda. I just love that brand! I just found another one though, Art Gallery. The fabric is like silk. I just made my granddaughter another quilt with all AG fabrics.
I use cotton thread mostly but watched a video with Leah Day and bought some poly that she recommended. I like it a lot. I use Superior, Aurifil and some that I bought from Craftsy.
I've experimented a lot with batting. My latest is wool but I use cotton and poly or blends as well.
I'm a real sucker for pre-cuts. I have more of them than yardage ( I think lol)