Flannel, Fleece, minkee, denim, or corduroy make very warm quilts. Good luck and have fun.

I made one with family clothes lots of denim, then put batting in and backed it in corduroy sooo warm!

Gee, my regular quilts were nice and warm when I lived in Maryland, Virginia and West Virginia. I think flannel sounds really great, but fleece would be really hot. I'd stick with the flannel and regular batting. If the quilt it too hot, it won't be used. You can add to a quilt, but you can't substract!

I always use fleece and poly batting on my quilts, and just do SID on them. I lightly spray baste them and have never had a problem. Good luck with whatever you decide.

I made one for Christmas with a flanned top, cotton battting and fleece backing. It was for my ex who takes coumadin and is always cold. He loved it.

Made a log cabin quilt with wool batting (washable). Very warm, but breathes which is nice.
Or you might make a pieced duvet cover for a down comforter. Or how about a really puffy polyester batting and then tie it. That will be cuddly and warm too. Happy Quilting.

I made one for my grandson with a light blanket as batting and flannel backing. It kept him warm and he loved the heavier weight on him when he slept.