One rumor rampant in the mattress world is that a firmer mattress inherently will provide better support for you. This is not necessarily true. We are all different, as such our sleeping preferences, and habits are different so this will not always be true. If you apply this logic to its extreme, then the floor is by far the best support you are going to find for sleeping. If the idea of sleeping on the floor doesn't appeal to you, then by all means dismiss this common misconception and trust your personal preference. Only you can know what mattress is truly right for you.
Two mattresses from the same collection may have different comfort levels, one may be plush, the other may be ultra firm, but the coil system within these two mattresses, (where the support comes from) will likely be exactly the same. Both can support your body equally, but you are going to prefer one over the other due to the comfort level the mattress provides.
In your search, find a mattress that delivers exquisite support, and choose the comfort level that feels right to you, this may be plush, or firm, or ultra firm. Just know that chances are the deep down support within a collection of mattresses is the same. This makes the comfort level the matter of choice when looking for that perfect mattress.