I don't suffer from the condition but I've been looking around the web to see what's on offer. A major problem seems to be that 'specialist' pillows for neck pain, which are reviewed by some people as being a wonderful solution to their pain problems, can be reviewed by just as many others saying that they found them totally useless. (So even if another ABer knows of something that works for them, it might not necessarily help you).
The NHS website does mention that you might also need to think about your mattress:
"Make sure your mattress is relatively firm – a soft mattress could mean your neck is bent while you sleep"
. . and your actual sleeping position:
"Avoid sleeping on your front, and make sure your head is in line with your body (not tilted to the side) if you sleep on your side"
. . . and provides this general advice about pillows:
"Only use enough pillows (usually only one) to keep your head level with your body"
Even though I don't suffer from cervical spondylosis though, I still suffer from a few aches and pains and need to find the best sleeping position. My own solution is to forget about expensive 'specialist' pillows and to simply buy some Asda 'value' ones. (At two for £3 they don't exactly break the bank!). Then I can choose to use them singly, in pairs or even, as they're so thin, folded in half. Perhaps some similar experimentation might benefit your own needs (and save you some money at the same time?).