Doing research on mattresses is like going down a rabbit hole that never
ends! It's hard to comparison shop, because the same manufacturer turns
out the same mattress and gives it a different name for various stores...sigh...
The only real conclusion I cam to (other than not buying super cheap ones which
could contain re-used materials) was to stay away from memory foam. Memory
foam (the brand name) gives off fumes that were immediately irritating to me,
and many say are irritating to everyone in time, even though they may not notice
them. (I have a nose like a dog ; ).
After pondering the purchase for way too long, I ended up buying one at Big
Lots, by Sealy, and love it. It isn't reversible, as all the old ones used to be,
but I couldn't see paying a lot more for this feature when this mattress is likely
to outlive me lol!