Which wicks are better ... silica, Stainless Steel or Ceramic
How would you make a wick out of cotton ball, just twist it?
Cotton.
But to the original question...it depends on the device and your personal preferences. I've seen many people tout the pros and cons of each and I think the answer is subjective.
I have not tried ceramic but between silica and SS I would say SS. But it depends on what it's in. Silica (or cotton) works best in rebuildable dripping atomizers (although I've seen folks use SS effectively as well) and SS works best in RBAs (but I've used silica effectively as well). Some people (myself included) have had good success with hybrids (silica wrapped in SS) in their RBAs. I've seen SS in a Protank (that couldn't have been easy...lol). Some people don't like the taste of SS and some don't like silica. You may just want to experiment and see what works for you.
Sooooo...to answer the original question....cotton.