Pillow firmness is determined by the type of filling. The aim is to get the correct support for sleep that will leave you refreshed, and while care levels might be a consideration it all comes down to what is most comfortable for you.
Are natural fibre pillows better than synthetic fibre pillows?
There are great benefits for both kinds of pillow, so it all depends on how you like to sleep. Generally speaking, natural filled pillows offer special support, where synthetic fibre pillows can be used to create any level of firmness. If you sleep on your side you’ll benefit from the full head and shoulder support of a memory foam pillow or down pillow to keep your spine aligned.
Front sleepers need to minimize neck strain so down or super soft synthetic fibers will be all you need for undisturbed slumber. Back sleepers are most comfortable with shoulder support, so the medium firmness given by mixed feather and down or medium synthetic pillows are ideal.