…this pillow, because I sleep on my back.
I’ve always been a very quiet sleeper, without a whole lot of position changes during the night. When I was a kid at camp, I used to pride myself on being able to slip into my bed at night so carefully that I didn’t disturb the covers much and could even leave them all tucked in, and then in the morning get out again so that I only had to smooth them over a bit and not make the bed at all. Success!
That doesn’t quite work any more. But when I hurt my back and arms many many years ago, I found the best sleeping position for myself, on my back with pillows under my legs, and have stuck with it ever since through thick and thin. I had no idea at the time that it might reduce the production of wrinkles, but hey, I’ll take it.