A good set of flannel sheets should be so warm and inviting that it’s hard to leave them on a cold morning—if you don’t want to stay in bed all day, they’re not doing their job.After putting in almost 200 hours of research and testing, and trying dozens of flannel sets since 2016, we still love L.L.Bean’s Ultrasoft Comfort Flannel Sheet Set. It’s one of the softest, sturdiest, and coziest flannel sets around.