The best firm mattresses will grant you a night of peaceful and supportive sleep. Most of the entries in our general best mattress guide run medium-firm, which caters to a wide array of sleepers. However, if you struggle with backaches, are overweight, or predominantly sleep on your stomach or back, a firm mattress may be more suitable for you. Below, we've rounded up five of our rock-solid recommendations (so to speak). We can vouch for several of these beds personally as we've tested them...