Adjustable pillow height
Coop Original Adjustable Pillow
Coop lets the sleeper remove or add fill rather than commit to a fixed pillow height. That makes it easier to tune the pillow to a mattress and preferred position.
Why it ranks here: First because adjustable height accommodates more preferences.
The tradeoff: Adjustment takes experimentation; loose fill needs careful handling.
Based on published review evidence and product information.