Depends on what I want the quilt to do.
If I want it real traditional, or if I want it to be a true, warm bed quilt, I use cotton.
If I want it lightweight and "breathe-y," that is to say not hot, then I use polyester.
If I want it thin and drapable, such as in a mini, then I use a very thin polyester.
If I want it durable such as a tabletopper then I use cotton - which also accommodates possible hot dishes.
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