A good mattress should last 7–10 years. Look for a warranty that covers (indentations) of at least an inch. Be aware that warranties usually require you to use a proper foundation or bed frame; placing a new mattress on an old, sagging box spring can void your protection.
Your primary position determines where you need the most support: buying a good mattress
The traditional choice. They offer excellent airflow (sleeping cool) and a bouncy feel but can lack the pressure relief of modern foams. A good mattress should last 7–10 years
A natural alternative to foam. It’s breathable, durable, and has a "responsive" feel—it bounces back faster than memory foam. buying a good mattress