Flannels are one of my favorite pieces for fall and winter! They're an essential and you really can't go without them. I recommend investing in some quality flannels from L. L. Bean; they are the thickest and warmest by far. I also find these last the longest and resist wear. If you want a really cheap alternative, Walmart has good flannels in the Men's section for under $10. J. Crew and Madewell are also my go-to for flannels. I've linked below some of the best options I could find online. Happy flannel-shopping!