Hi Guys!
We are the manufacturer of the pillows that Debra mentions in the above comment. Kapok tends to be quite soft, and we market it as a down alternative. It's a loose fiber that is permitted to float around inside the case, and thus gives a very similar feel to down. It's so light that it will float on the air (the girls in the pillow department have to wear a mask when they make these, so that it doesn't fly up their nose when they breathe!). Naturally hypoallergenic, Kapok is incredibly soft to the touch, hence the name "Silk Cotton", which is often given to it, particularly in India. The Kapok or Ceiba Tree only grows in a tropical environment. It's even used in life preservers because it's so buoyant. It tends to provide a very soft, yet supportive feel when used in pillows. It's also incredibly resilient, and you can keep fluffing it back up for years to come. With mine, I'll toss them in the drier on the air cycle (NO HEAT - Heat will actually singe the edges of the fiber on the interior) with a clean sleeve of tennis balls for about 5 minutes, and they fluff right back up. It's a really resilient fiber. The Kapok or Ceiba Tree only grows in a tropical environment. It's even used in life preservers because it's so buoyant.

Cotton is a whole different animal when it comes to pillow fills. Cottons tend to provide a firmer surface, and are typically stuffed with layered cotton, so it's good to keep them level to avoid bunching. You can also fluff them in the drier on the air cycle (NO HEAT) if they seem to get too compacted.

I hope that this information helps :). Best of luck to you in the search for a perfect pillow!