Hi trulyblest,
Southerland is actually the 15th largest manufacturer in the US (see the article here).
1.) In terms of quality?? Your personal opinion?
A mattress is only as good as the quality of the materials and components it’s made of so to make any assessment of quality you need to know the density of any memory foam or polyfoam and the type and blend of any latex along with information about any other components of the mattress (such as the cover, quilting material, or innerspring etc). In most cases the density of the foam materials will be enough to give you a good indication but without this you are making a blind purchase and there is no way to know the quality of a mattress or make meaningful comparisons with other mattresses.
mLily and BedBoss along with EasyRest inc all use Chinese manufactured memory foam that is made by Health Care Foam* in China and are Certipur certified. They make some good quality and value mattresses as long as you are comfortable with some of the uncertainty with foams that are made in China (see post #2 here and post #6 here). All of them will generally provide the density information of their polyfoam and memory foam and the retailer will either have this or can make a phone call to find it out (providing you with this is part of the job of all good retailers and manufacturers). If you post the information here about the specific mattresses you are looking at I’d be happy to give you my thoughts about their quality.
ADMIN NOTE: *Removed 404 link|Archived Footprint: certipur.us/pages/for-industry/find-a-foam-supplier/hk-foam/
A “value” comparison with another mattress needs the “mattress only” price and the information about the specific materials in each mattress. Post #12 here has a list of online memory foam manufacturers that can provide some reference points for “good value”. Once you know the specific materials in the mattress you are considering then you can look for a mattress that has a similar design and components and similar density memory foam in the same thickness.
The linked post in the previous question has some of the better sources of memory foam online that I’m aware of. As far as local it would depend on where you lived and what was available to you and if you let me know your city or zip I’d be happy to let you know of any of the better options or possibilities I’m aware of.
In very general terms … these three manufacturers tend to have good quality value memory foam mattresses but it depends entirely on the specifics of the mattress you are considering because what is in a mattress is always much more important than the name of the manufacturer on the label.
Phoenix