Though people are too diverse in their mattress preferences to be properly studied, most sleep experts agree that firm is better. That's because a too-soft mattress won't support your hips and spine, and you could wake with pain in the morning. Instead, try to find a balance with a mattress that's firm enough to support your weight, but still has plenty of cushion and bounce for comfort.
WebMD recently interviewed sleep experts to find out what things to consider when shopping for a new mattress. If you're in the market for one, you may want to take a minute and see what they had to say.