I am a serial pillow purchaser. For a long time I went through as many as a dozen pillows a year trying to find one that helped, for the same reason as you. I have cervical instability and had a surgery to fuse C4 through C6 in my neck and still have herniations and bulges above and below. Excruciating. Sleep was never restorative and I would often wake up and more pain in my neck that I went to bed with.
The pillow I’m linking below is the only one I have found that was helpful. It is memory foam with a gel cover and, because of the shape, it keeps my neck from tensing up while I sleep and gives me the right amount of support. Mind you, I have trained myself to only sleep on my back (even though that is not my preference) so that my neck stays in alignment. When I use this pillow I place my head in such a way that the “wings” that come down on either side of my head and sit on top of my traps. This helps keep my shoulders relaxed and helps with the inevitable scrunching/muscle rigidity I get while sleeping. It has been a lifesaver. Sleep Innovation Pillow
Seconding this one!! Switching to a memory foam pillow was a lifesaver. So much that I bring it with me when I travel if I can! Mine has a little divet like this one: https://www.amazon.com/Sleep-Innovations-Versacurve-Multi-Position-Warranty/dp/B01FAZR9NU
I’ve tried ones that are shaped like regular ones and those didn’t work very well- I’m a side sleeper.