This is a very common question for people shopping around for memory foam beds and it is a very tough question to answer as there are a just too many variables to consider. It would be akin to asking, which car is the best? Or which is shampoo is the best? Now, while giving a specific answer is difficult, pointing you in the right direction so that you can refine the search yourself is very much possible.
Before you begin your search there are a few basics you have to know about memory foams. Memory foams have their unique property of being able to mold itself perfectly to your body contours and provide exceptional support.
This property of memory foams is derived from the chemical bonding structure of its components and the manufacturing process resulting in the creation of millions of minute cell structures. Here are the common qualities present in high quality memory foams
Density is one important factor in choosing the best memory foam mattress. This is because with greater number of the ingredients molecules within the memory foam results in more bond formation which gives better resilience and durability. Density is given in Lbs. per cubic foot. The best memory foam mattresses generally have density ratings between 4lbs to 6lbs and are guaranteed for at least about 15 to 20+ years.
Inert and non toxic chemicals
All the best memory foam mattresses address health issues and will ensure that the ingredients used are fully inert once manufacturing is completed. Also adhesives used should be nontoxic as generally cheaper mattress uses cheap adhesives which can gas off for months or years.
Quality fire retardants
Fire retardants are an important issue with memory foams because untreated memory foams are highly combustible. US laws require compliance with FR test for all mattresses sold. Non-toxic fire retardants for example Kevlar based FR will be used in all the best memory foam mattresses. Cheaper mattresses may contain PDBE or other chemicals which can be highly toxic.
Aeration and absorption
One common problem with memory foams is their heat retention. Best memory foam mattresses all integrate designs which increase aeration to eliminate heat retention and promote breathability. Also all the best memory foam mattress comes with high quality covers which are specifically designed to increase absorption of fluids and oils all the while serves as barriers to water and dust mites.
Overall, apart from individual tastes in comfort and support, these are all the qualities that you want if you are looking for the best memory foam mattress.