Cotton is absorbent and breathable, making it useful for next-to-skin basics. Wool offers warmth and temperature regulation for knitwear and outerwear. Blends combine useful qualities from different fibers.
Fiber percentages are only part of the decision. Yarn, weave, weight and finishing can make fabrics with the same composition feel completely different.
The right choice depends on climate, wearing frequency and the care routine that fits your life.