ttran, thought I’d chime in not based on a huge background of mattress knowledge but because I’ve been in your shoes and wrote several of the companies you mentioned. Dynasty, Slumber Solutions, any of the Zinus brands (Night Therapy, BestPrice Mattress, Vivon, Spa Sensations), basically most of the Amazon listings and typical brands of lower cost “bed in a box” type mattresses from Overstock, Wayfair etc are similar. They’re a more affordable product and not necessarily bad but they’re hard to filter through. Like Phoenix said, most of these use 3-3.5lb density mem foam. Some use 4lb or even 5lb, but there’s different qualities of memory foam so one brands 5lb may not be all its’ cracked up to be.
It’s difficult to get the information out of them (I know from contacting Sleep Revolution and BestPrice Mattress, along with their parent company Zinus - and from my email correspondence with Linenspa). Poly foam density can give a better idea of general durability, but it can’t tell how it feels or how firm it is. So it’s a chunk of the answer but not the whole thing. Trying to sort through the sales pitches can be a bear. They use terms like ‘airflow’ foam when more often than not it’s really eggcrate foam. How well it transfers or channels air through the middle of the mattress to keep people cool is debatable since when you’re laying on it, it mashes flat. It’s not exactly a structural air duct inside with forced air flow. They promote huge warranties because the coverage is minimal and there’s no comfort guarantee. Foam softening isn’t covered. Significant body impressions aren’t covered until they’re beyond what most people would find tolerable. The biggest part of the problem is suitability and comfort since most can’t be tried out even for a few minutes in a store.
In my own searches into mem foam mattresses, I started to get sucked into the sales hype. Some brands will say gee, why are you paying x amount for a mattress which is all poly foam with only a couple inches of memory on top? Our mattress xyz gives you a full 5" of the “good stuff” which makes them sound better. The problem with 5" of memory foam is the way memory foam acts. It’s firm(er) (depending on ambient room temp etc) initially. Then when you lay on it, your body heat softens it giving the memory effect. It doesn’t smash flat, so it has some support but will generally continue to sink during the 7, 8, 9hrs you’re asleep. That can end up being a deep cradle with risk of throwing the body out of alignment. Maybe not in the first hour or two, but maybe halfway through the night. More isn’t always better.
I can relate a bit to what Phoenix is saying about the personal value and the risk involved. A family member of mine needed a new bed. Maybe it was beginners luck, maybe it’s because she’s physically smaller than some (around 5ft, 125lbs). She got a Spa Sensations 12" mem foam from WalMart. It had great reviews and I didn’t know what I do now from the months I’ve been a member of this forum. The mattress unpacked properly and swelled up to its’ proper size (some don’t fully expand). From the info I could get from Zinus, it uses 1.8lb density base foam in 2 different firmness layers and a 3rd layer of 3lb memory foam. Still nothing indicating firmness really and everyone has different ideals anyway. Initially it was quite firm on top, 7mo later and it’s a bit softer. This may be due to ambient temps, the difference between 65 degrees and 85-90 degrees (and yes the a/c is running lol). Luckily for her it’s working out great so far. She found good alignment and it’s comfy for her. I gave it a try since I needed a new bed also. It is comfy, in my opinion. However I’m 5’6 and around 190. After laying on it for 20-30min, despite feeling it was comfortable I wasn’t in alignment. I could feel my hips sinking laying on my side and back both. Had I based my decision off the trusted personal ‘review’ of a family member, I could very well have been disappointed. She wasn’t trying to steer me wrong, we’re just very different in physical size and what does in fact work for her, didn’t for me. It’s not a bad mattress, it’s not uncomfortable - it just isn’t supportive enough for me and therefor doesn’t work. For 300-350 depending on sales for a queen, I really wanted to like it. Had I jumped the gun and bought it, I have a feeling I would have been disappointed and rather than saving a few hundred, I would have spent a few hundred on something that didn’t work and had to start over. So far it’s only been 7mo so only time will tell how it continues to hold up for her.
That’s why someone can’t tell you what a good mattress will be. They can only tell you what works for them and despite how trustworthy and sincere they are, what works for them just may not work for you. Which will pretty much be a risk for any online sight unseen purchase. If Phoenix or anyone else were to tell you hey, this a great mattress. It feels incredible… and you found out it wasn’t comfortable for you or didn’t work for you in terms of support (which no one can really know but your own testing), your disappointment will fall on whoever made the suggestion. Just like my family member had no way of knowing that what worked so well for her turned out to be wrong for me. It sounds vague or non committal and when we’re in need of a mattress we just want answers. The best mattress in theory of materials for durability performance, longevity etc could end up being your worst nightmare if it’s too firm/soft or if you sink too deeply and end up with restless sleep or back and neck stiffness. Because there’s every body shape configuration and sleeping habit/position conceivable, there’s no way to estimate how a mattress will work out. Whereas something like car tires, they know roughly the weight range of common vehicles, the forces applied during turning, the friction wear over similar road surfaces. With more stable ‘variables’ they can rely on, it’s much easier to say tire xyz is a 50k mile rated tire. The more constant and reliable the variables, the more consistent the outcome. Mattresses just don’t work like that unfortunately.
If you are considering different mattress types (mem foam to latex), the often repeated advice is to try them in person if possible. I had to go several towns away to get to a mattress store and luckily they had latex beds to try. I’m so glad I did because not being familiar with it, there’s no way to ‘guess’ at what it’s like. That really is the best advice. I’m still amazed how a small piece of latex 3" thick can be easily smashed flat under my hand. Sitting on a ‘test block’ 16x16" by 6" thick, it disappeared beneath me and I thought no way will this work. Laid down on 6" thick in a twin size and felt like being on a pool float riding on top of the water. Had I bought blind, I’m sure I would have gone way too firm for my liking. It’s like trying to describe “silly putty” to someone who’s never seen it, trying to tell them if you pull it slow it stretches - if you pull it fast it will break and snap - you can roll it in a ball, roll it paper thin, press it on a newspaper and it will peel up with a copy of the image on it. No way to really grasp how it can be all those things.
