Whether your preference is to sleep organic, like the green Avocado mattresses; use a cooling mattress; or sleep on your side, back, or stomach, this is the most important factor when selecting the right mattress brand: one that keeps your spine aligned while applying supportive pressure evenly (kind of like a hug). Ultimately, the best mattresses allow us to sleep happily and soundly. The rest — like size, price, and material preference — is pretty variable. Each of the R29 testers ahead used their own unique set of parameters to evaluate the individual mattress they tested — everything including foam models, hybrid innerspring and padded, even sustainably made mattresses.