I don’t know if this advice still applies these days but I have been told to avoid the brands that start with a “see” sound, like sealy or serta.
I have been happy with rubber mattresses. They have varying firmness sheets that comprise of the matress.
If you go in store be sure to lay on a potential mattress for an hour. Just plan to hang out on it.







It disables JavaScript JIT by default, IIRC. If you haven’t turned it back on, give it a go.