Nobody dare to say that which is better between silk pillows and cotton ones. We could say that each of them has its own advantages over others.
The deep impression that cotton leave us is that we may feel warm and cozy, but it is a highly absorbent material that draws moisture from our skin and hair as we sleep. Actually, we need the oils that are leached by cotton to keep our hair calm and our skin supple. A satin pillowcase, on the other hand, allows our face and head to move easily on its surface, avoiding the friction and damage caused by cotton.
For the purpose of being beautiful and healthy, silk satin pillowcases should be in your shopping list.