Hi nandha,
Welcome to the Mattress Forum! 
[quote]Went through many posts and your valuable suggestion and response in this forum and I really appriciate it. I am posting my problem below to find the mattress I want:
Now I am looking to buy a firm mattress and wanted to make sure that I am getting the correct one to use at least for the next 5 years. I started understanding the basics about buying mattress and started searching online for information for the past two weeks and today fortunately found this forum.[/quote]
Just in case you haven’t read it yet … the first place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that you will need to make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort” and PPP (Posture and alignment, Pressure relief, and Personal preferences) that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists (based on all the parts of your personal value equation that are most important to you).
Unfortunately this isn’t unusual with mattresses that use too much lower quality and less durable materials in the upper layers of the mattress.
While I can’t speak to how a mattress will feel or how different mattresses will compare in terms of comfort and PPP for someone else … outside of “comfort” and PPP the most important part of the value of a mattress purchase is durability which is all about how long you will sleep well on a mattress. This is the part of your research that you can’t “feel” and assessing the durability and useful life of a mattress always depends on knowing the type and quality of the materials inside it regardless of the name of the manufacturer on the label or how a mattress feels in a showroom or when it is relatively new so I would always make sure that you can find out the information listed here so you can compare the materials and components to the quality/durability guidelines here to make sure that there are no lower quality materials or weak links that would be a cause for concern or compromise the durability and useful life of a mattress you are considering before making any purchase.
All the major brands (such as Sealy/Stearns & Foster, Simmons, and Serta) tend to use lower quality materials in their mattresses than most of their smaller competitors that will tend to soften or break down prematurely relative to the price you pay and I would generally suggest avoiding all of them completely along with any mattress where you aren’t able to find out the type and quality/durability of the materials inside it (see the guidelines here along with post #3 here and post #12 here and post #404 here).
If a retailer or manufacturer either can’t or won’t provide you with all the information you need to make an informed choice and make meaningful comparisons with other mattresses … I would walk away.
I don’t make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort” or PPP or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress) or “theory at a distance” that can possibly be more accurate than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial)or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
I or some of the more knowledgeable members of the site can certainly help you to narrow down your options, help you focus on better quality/value choices that are available to you either locally or online, help you identify any lower quality materials or weak links in a mattress relative to your weight that you may be considering, act as a fact check, answer many of the specific questions you may have along the way that don’t involve what you will “feel” on a mattress, and help with “how” to choose but only you can decide which specific mattress, manufacturer, or combination of materials is “best for you” regardless of the name of the manufacturer on the label or whether anyone else (including me) would have the same criteria or circumstances or would make the same choice.
The better options or possibilities I’m aware of (subject to making sure that any mattress you are considering meets the quality/value guidelines I linked earlier in this reply) would be listed in post #7 here for the Monroe Township/Newark, NJ. region or post #2 here for the New York City region (there will be some overlap between them).
Phoenix