Hi hokka,
Have you read the tutorial post here?
It has the basic information, steps, and guidelines that can help with “how” to choose the best mattress for you … and know how to avoid the worst ones (including the major brands or any mattress where you aren’t able to find out what’s inside it). There are too many unknowns, variables and personal preferences involved for anyone else to choose what mattress is best for you because nobody else can feel what you feel on a mattress (see mattress firmness/comfort levels in post #2 here).
It also has a link to some of the better online retailers and manufacturers that I’m aware of once you’ve decided on the type of mattress you prefer based on your local testing and preferences.
Phoenix