Denim and leather are both a must in my closet. But do I think leather is replacing denim? Definitely NO. I use denim almost every day and it's hard for me to decide not to wear a pair of jeans. In case of leather, I prefer wearing it when I go out at night. A jacket and a skirt are basically the only leather pieces of clothing I need in my closet which I could wear occasionally.
So which one do you prefer or which one you wear the most?