I have an Airweave futon mattress because I have a lot of scents sensitivities. The mattresses are made of coiled plastic and have two washable covers. The mattress itself can be removed and hosed down so if I do spill something on it, I can clean it easily and I don't have to worry about mildew.
I have found that sleeping on a thinner and firmer mattress gave me more energy but I don't think that is universal. I think it helped my posture. If I were bedbound I am sure I would opt for something softer!
I have an old innerspring mattress that is firm underneath but soft on top--one of the older versions of a pillow top. My mom also has an innerspring mattress but one of the newer thicker versions of the pillow tops. If you have a lot of muscle aches hers feels better than mine for that.
The company we purchased from is mostly local, I think. They allow adjustments for one month afterward and then for the life of the mattress but it cost more for the adjustments later on--like $60 pick up and deliver fee or something like that.
We also purchased a well known name brand innerspring mattress years ago from a furniture store. Little me could carry that with one hand. I didn't try that in the store but it made me realize later on that there wasn't too much support inside if it was that light. That one, even though it was a pillow top was bad for both my mom and me. I tried it and then she offered to try it. Unfortunately, their return policy on mattresses was "no returns allowed." I didn't see that when I bought it. (I should never have gone shopping after working a full day in the office.)
I'm saying all that to say if you are shopping for a mattress I think it would be better to buy from a company that makes their own mattresses and also offers future adjustments or at least free returns in case it turns out to be a bad purchase for you.
I don't know about the new memory foam mattresses but just laying on one in the store made me itch like crazy because of my MCS (multiple chemical sensitivities), even through my clothing. (Just another consideration.)
My mattress is from "Tuft & Needle" and I am really happy with it. They deliver it to your home in a box and then it expands into it's regular shape ... It is the exact firmness that I like and had no smell of VOC's or chemicals when it arrived. I've had it since 2015 and still in excellent condition.
I'm emaciated and bedbound much of the day so a soft mattress is important for comfort. The description says: "Careful construction guarantees no prohibited phthalates, no ozone depleters, no CFCs, no mercury, no formaldehyde, no PBDEs, and low emission (VOCs) for indoor air quality." But, it did have an odor when it arrived so I had to leave it for a couple of days to offgas.
The description also says: "The first layer is a 1 inch bamboo charcoal memory foam layer sewn into the soft outer cover. Bamboo charcoal is especially good for sensitive skin and has better thermal regulation." Some people complain that memory foam causes them to heat up too much. I haven't noticed that problem with this bed but it's the only memory foam bed I've ever owned so I don't have anything to compare it with.
I have a proper orthopedic mattress I think it is, I've had a lot of back issues (unrelated to ME/CFS so that is important to me). I did though have to buy a memory foam to go on top of it as without that with my sensitive body I found it too hard (I need something firm but soft). The memory foam topping I brought is a special one which is infused with something so it's more cooling than standard memory foam.
I had to get a second hand mattress due to my MCS as new ones can be an issue for me.
I had a sleep memory mattress with the numbers to adjust and that seemed ok, but it broke and is very expensive to fix...I ended up buying just a regular soft mattress but out lots of foam egg crate pads on top where my pain points are worst...they are inexpensive and I can move them around.I have several layers and different densities for where my pain is worst. When I worked with kids with severe physical disabilities some of them used waterbeds.