Is the problem height, firmness, warmth, texture, or shifting?
Change the pillowcase before changing the pillow.
The same pillow can feel different on a softer or firmer mattress.
Height matters
A pillow that is too high can feel crowded. A pillow that is too low can feel unsupported. Height also changes with mattress softness. On a soft mattress, your shoulder or body may sink more, changing the height that feels right. On a firm surface, the same pillow may feel different.
Firmness is not the whole story
A firm pillow can still feel comfortable if the height is right and the cover feels smooth. A soft pillow can still feel awkward if it collapses too much or shifts during the night. Separate firmness from shape stability and fill movement.
Use the pillowcase test
Sometimes the pillow is not the problem. A rough, tight, slippery, or warm pillowcase can change the feel. Try a different pillowcase before replacing the pillow. Also check whether the protector or cover is pulling the pillow into a shape you do not like.
Adjust before replacing
If the pillow is too tall, try a thinner case or remove extra inserts if it is adjustable. If it is too low, test a folded towel under the pillow for a night to see whether extra height helps. If fill bunches up, shake and redistribute it before deciding.