Memory foam is overrated IMO. It doesn't breathe and I hate sleeping warm. You will waste a lot of money on a/c on nights you wouldn't otherwise need it if you use memory foam. That said, it is probably the most comfortable for pressure points and joint pain, but only until it breaks down, which doesn't usually take long - especially since it's usually a total scam (2 inches of memory foam on top of 10 inches of polyurethane or something like that). Synthetic foams are filled with little air pockets to make them "cushiony", but air pockets eventually flatten. 100% latex is sustainably soft because it's part of the molecular structure of rubber. Latex mattresses don't go bad if you keep them clean and dry. They don't have anywhere near as many synthetic chemicals as most other mattresses (usually just latex, a fire resistant cover which you can remove, and a cotton cover), and they're hypoallergenic unless you're allergic to latex. Bed bugs supposedly hate them, too. They're very comfortable, although people with a herniated disk supposedly have trouble with them. They don't shake when your partner shifts in bed. They are floppy, heavy, and hard to move, and you need a strong foundation but not a platform (there should be slats underneath with small gaps so the bottom can breathe). Inner spring mattresses are junk IMO. All kinds of suspicious, cheap, synthetic cushioning to put lipstick on a pig of a support system. Coils are very cheap and mattress manufacturers are making a killing on people who buy them. You're paying for a bunch of air for gods sake. I guess the gold standard is buckwheat. I have a buckwheat pillow and it's amazing. It conforms exactly to your shape and then stops moving completely. The hulls cling to each other in a way that allows them to move when you're trying to carve out a comfortable sleeping position, but stops them from sagging once you're settled in. And unlike memory foam, they breathe because they're concave. I'm thinking of getting a buckwheat mattress as well, but I spent $1500 on a latex mattress from plushbeds.com 5 years ago and it's working well for me. It should last 20 more years at least. Bottom line, I recommend natural bedding materials, and not just on principle - they're actually the most comfortable and durable in my experience.