If buying new, I go to Walmart or Dollar general and get the polyester blankets. If thrift shopping, I just check the blankets for wear and serious stains. I then wash both used and new ones. I feel once they are inside the quilt, it makes them heavy, especially large quilts. My daughter prefers the sheet or thin cotton blankets be used, they are just the weight she likes, but I prefer heavy ones. I like to use blankets when tieing. They are sturdy, and hold up to years of use. My kids still have theirs I made for them 23 and 21 years ago. Good luck
Deb