What mattress brand do you recommend?

Sleep Like the Dead is a fantastic mattress review site. People have so many different ways of valuing things that recommending my mattress is useless to you. This will allow you to identify what you value, perhaps realize some things you had never thought about, and then narrow down the options to then ask questions about people who purchased mattresses 1, 2, and 3 and maybe get some more useful responses.

Unfortunately, brand is not a good proxy for suitability to you and your body (height, BMI, body type and weight distribution, sleeping position, etc). The only way to find the "right" mattress is to learn what your body wants.

That is to say, a cheap crappy mattress might be the most comfortable thing you've ever slept on (but won't last due to crappy materials and construction), whereas an expensive premium mattress may give you horrible sleep (even though it's able to last for 20 years).

An overwhelming majority of internet-based consumer advice has been poisoned by brands that purchase favorable coverage, it's very difficult to find objective information (not that reviews mean anything, since the reviewer has no idea who you are and can't tell you how a given mattress will suit your body). However, Sleep Like The Dead (already linked in another comment) is a resource that is at least impartial. The Mattress Underground website has some good writeups on how to orient yourself mentally before wading into the mire.

It's worth taking the time to understand what makes a mattress good for you, because there's no other way to get a good mattress.

I recently changed mattresses and went to 3 stores: a chain, a discount place, and IKEA. Don't rush yourself checking out mattresses -- I recommend at least 10 minutes per, 20 if you can stand it. Take your shoes off, lie down, get comfy, and stay there for a while. Spend time in all the positions. Roll over to the edge and check the firmness there. Don't worry about the salesfolk, their job is to guide you to the most expensive ones which are of course going to be pretty nice. (We ended up going with IKEA.)

I think it's pretty hard to judge any online mattress. But a lot of them do have an N-night trial which can be pretty lengthy and give you plenty of time to really get to know it.

I have a Casper, it's comfortable, not too firm or soft. They have all kinds of options on their site now, back when I ordered they only had one. I guess the one they call "original" now is the one I have.

So I think it may depend on your life stage and situation a bit as well.

So my husband and I got a sleep number bed split top king but we knew we'd be living in our house for at least 5 years and wanted a huge bed as we let our dogs cuddle with us. It was well worth it!

Not going to lie sleep number feels kind of cultish but at the same rate it kinda earns it in our book. I do hate the price of sheets. However the ability to be tilted up partially at night especially when pregnant was a godsend.

So are you moving if so get something simpler. One person a king bed might be too big. Things like that, but overall love my bed

We have a Novaform one that we bought at Costco. Have had it for about 3 years now and are still very happy with it. It's pretty similar to any other mattress that comes rolled up in a box.

Love our tempurpedic

I did some searching online, and found great reviews for Plank Mattress and a local mattress retailer had it available to try. We loved it, however somewhere in the game of telephone someone fucked something up where they made a King mattress, and shipped it, but we ordered a CA King. We called multiple times asking about our delivery, ended up having to call Plank directly, who then said, "oh shit" and we had our mattress 3 days later cross country.

I'm really happy with my purple mattress a few years into it. Everyone who sleeps on it loves it, and I'm never sore in the morning whatsoever. Granted, my sister got 2 delivered by accident, and sold me her 2nd one for half off, but I plan on using it for 10 years plus.

I have a Purple Premier 4 and it's the best damn mattress I've ever tried. The responsiveness of springs topped with Purple; a human person being uncomfortable on this thing is simply inconceivable. I'd recommend it to anyone.

I have found Tempur-Pedic to be consistently well reviewed and well liked, although they are usually more expensive than most newer brands.

Aside from that, I would look for really good return policies and buy from an online retailer. They do tend to have way better prices, unless you're willing to go into a store and literally negotiate for the price of your mattress. Plenty of places will negotiate because the markups tend to be substantial, but if you just want to click "buy" and know you're getting a decent price, pick an online retailer. Again, one with a proven easy return policy.

I've tried Casper, Leesa, and Purple, and honestly I've been loving the memory foam overall, but you do need at least 2 days to let them off-gas and get rid of the smell.

Anything without internal springs will not give good support around the edges. This is because there's just no mechanism to help add structural integrity to the edges. If you don't frequently use the edge (for sitting or sleeping) then this is a non-issue.

Hybrid mattresses are supposedly much nicer than foam if you like extra support, but they tend to be much more expensive. I haven't tried one personally though.

Last two times I bought from store brands (that were not tempur-pedic) I was put through such awful support when I would get permanent potholes in the mattress that both times I eventually gave up trying to get a replacement. I've been much happier with online retailers with better return policies. You do have to be willing to be without a new mattress for a while though if you're going to test them out in-home. I guess you could technically order two or three mattresses at once and return all but the best, but that's a huge up front cost, though probably the best option if you can afford to do so and have space for multiple mattresses.

You didn't mention your location and they're pretty limited in availability, but I've had an Aireloom for the last seven years or so and it's been the most amazing thing I've ever slept on. They are not cheap and they are not portable, but I spend 25% of my life on a mattress :P

As far as brands I don't like, a lot of the bed in a box mattresses have really bad edge support and always make me feel like I'm rolling off.

You might consider building your own with layers of latex or memory foam in various densities. Lots of info on /r/mattress that I learned about it

We weren't satisfied with most of the easy to find brands. So I did some looking for less popular brands and found King Koil. We bought a king size probably 6 years ago and it has held up very well. I think it might be more common in the Northeast but on the West Coast you have to look up nearby retailers.

We went with a Brooklyn signature hybrid, firm queen that was on sale from 1k to 800 USD. I wanted something really firm but still provided some of the advantages of foam (like not disturbing a sleeping partner when I go to bed after her) and we don't really have any complaints. Had it for about 3 years now. I wish I would have gotten the king, my kids love pushing me out and taking over my spot to snuggle with mom in the early mornings

Pretty happy with a Charles P Rogers lifetime hybrid mattress we got earlier this year - firm/supportive but the comfort layer conforms to my side sleeping really well. (190 lbs)

I am in the same boat and after my research I've decided I'm going to try going the DIY route. After all, most mattresses are made of very similar materials, and going DIY means that if the mattress starts sagging in the future, I can open it up, find the culprit layer and get a new one for a fraction of what it would cost to get a new mattress.
If you're willing to spend a bit of time reading up on the subject, as well as going to mattress stores, trying similar beds out, and asking about specs like IFD ratings and foam density of material, it seems like there's an opportunity to save big and have a mattress that could last much longer than a big name brand one.
I haven't gotten my materials yet, but I plan to get an 8" pocketed coil layer, a 3" soft Dunlop latex layer, and an 11" zippered mattress cover. I'm hoping it goes well but I'm prepared for the possibility that it might not.

Lots of good advice so far, but the one thing I haven't seen mentioned (sorry if I overlooked it) is to find those tests that lets you input your weight, sleeping positions etc to estimate what types of mattress you should be looking for.

For multiple people with different bodies and sleeping positions getting individual single mattresses with a big, whole topper can be a very good choice.

I have a bed from IKEA with a mattress, topper and bed slats all tailored to the results a couple of those tests suggested. Mattress and topper do not belong to the same set. I love it still after several years, but ex's back absolutely hated it. We had/have very different body types and sleeping positions.

Another thing to consider is how willing you are to turn and flip your mattress for longevity? If you don't care about that, mattresses with zones can be an option to look at.

Box ones can only be turned so head and foot switches place. If you have the space for it. Regular mattresses can also be flipped over.

I got one with different zones so it can't be flipped around at all. I know that means specific comfort in exchange for a shorter mattress lifespan. But I am aware of that, and took that into account.

I don't think I've ever had anything other than IKEA mattresses. I still use them but as an adult I have at least invested in memory foam mattress toppers, and it definitely works for me. However apparently you need to change those out every few years? Hope this helps somehow!