Wirecutter is owned by the NY Times and does very good reviews. You can also spend a few bucks to buy a Consumer Reports subscription for a month and access their huge testing database and years of experience.
When we purchased our mattress ( a Vi-Spring ) the store only accepted our order after we had lain on a matching configuration in-store for 20 mins. Or was it 30?
If felt odd lying in the middle of a shop but apparently it was the only way to enable the softness-exchange warranty. We could switch up or down one softness grade but had to find the starting grade like that.
Seriously though, thank you, I'll keep that in mind for my next major purchase.
Online mattress sales became popular precisely because of those scummy tactics, as well as very generous return policies, where you can actually use your bed for a significant amount of time before you make a decision on it.
FWIW I really like purple.
My current plan is to have either a spring or dunlop latex base, with then 3 inches of firm dunlop and 2 inches of medium dunlop latex on top. Side sleeper (mostly)