Check out Wirecutter for testing, reviews, and discussion (may require subscription): https://www.nytimes.com/wirecutter/reviews/best-bed-pillows/

I've been using their reviews on lots of items for years and very happy with most of what I've picked up. They usually have budget and upgrade picks and explain the differences.

I've been through tons of pillow options over the years, never quite satisfied. Just picked up the Wirecutter back sleeper recommendation at $90 (Nest Easy Breather) and it is hugely more comfortable than what I had. I was also wary of spending that much but glad I pulled the trigger. Haven't had it long enough to know long-term, but I feel pretty confident with all the info in their review.