Which one is warmer - fleece or cotton flannel lined jeans?

[procon]

1. Its a trade off because they each have different properties and functions.

Cotton wicks moisture away from your skin, so if you stay dryer you won't feel chilled by damp clothing. Most fleece fabrics are manufactured from a combination of synthetic fibers, including recycled water bottles, and the fleece contains air pockets that trap in body heat which can keep you warmer, but is also absorbs moisture which will make you feel chilly.

The best solution is a combination of a moisture resistant body suit of cotton or silk fabric, this wicking layer is worn next to your skin. A light insulating layer like fleece or flannel goes on next. If a heavy insulating layer, like lined jeans or quilted outerwear is needed to trap heat in the body, that goes on last.