There are several reasons why you might consider a firm mattress:

Better Support: 

Comfort:

A medium-firm mattress is designed to provide a balance of comfort and support. It is firm enough to provide adequate support for your body, helping to maintain proper spinal alignment and alleviate pressure points, but also soft enough to provide a comfortable sleeping surface.

Good for different sleeping positions: A medium-firm mattress is suitable for a variety of sleeping positions, including back, side, and stomach sleeping. It can help keep your body in a neutral position, which can reduce the risk of developing aches and pains.

Helps with back pain: Medium-firm mattresses can be particularly beneficial for people with back pain. They can help alleviate pressure on the lower back, which can reduce pain and improve sleep quality.

Good for couples: A medium-firm mattress can be a good choice for couples because it can provide a balance of comfort and support for both partners, regardless of their body weight or sleeping position.

Overall, a medium-firm mattress can be a good choice for those who prioritize both comfort and support in their sleep. However, it's important to remember that everyone's preferences and needs are different, so it's important to try out different types of mattresses before making a purchase to find the one that works best for you.