The best pillow I have found is from EZ Posture Products. The pillow has several foam layers that are different thicknesses that can be added or removed to customize the height for side sleepers. I’ve used this for years. The developer of the pillow is an ABC(TM) chiropractor who now is retired from practice and devotes his time to making supportive products for ABC(TM) patients.
Back Sleepers: If you are using an “orthopedic pillow” (thicker on one side, thinner on the other) and have any discomfort in your body while you are sleeping, an “orthopedic pillow” is not approved. Use a hand towel and fold it up several times (5-7 layers thick) and put the folded parts under your neck. Let the tail of the towel trail over the top of the mattress.
WORD OF CAUTION: If your mattress is a pillowtop or has a noticeable sag in the middle, the back-sleeping instructions do not work. If you are trying to get a comfortable night’s sleep, then use these instructions with a firm guest bed that doesn’t have a pillow top or sag.
And if your mattress is sagging, a new mattress is your next purchase. Check the warranty with your manufacturer. Many patients have gotten replacements for their sagging mattresses if the sag is more than a certain depth. While I cannot guarantee what the most comfortable mattress on the market is, I personally like Denver Mattress’s Doctor’s Choice. Many patients over many years have been satisfied as well. The price is right and the product lasts at least as long as name brands that cost 2-4 times as much.