The right bed is like the right sofa. Different people like different things. Some like a soft cushiony model they can really sink into, others prefer a firmer, more shaped place to sit. In the same way some people prefer soft, springy mattresses and others prefer something harder. However, the way a metal or wooden bed will feel isn’t all down to the mattress. The actual influence of the bed is direct and significant.
One simple thing you can do before buying a new bed is experiment with the ones you already have. Do a tour of the bedrooms and try out the sleeping arrangements in each one. See if you prefer a firm feel or a soft one. Some of what you feel on a bed is the mattress, but if you like a harder feel, think about opting for a slatted wooden bed base rather than a soft springy divan.
A harder bed or a firmer mattress will not necessarily be better, health-wise. If you have back or neck problems many people choose a harder bed thinking it will improve matters, but that isn’t necessarily the case. The best bed for you will be the one you’re most comfortable in, and that is mostly down to personal preference. If you have serious spinal problems it’s always best to consult your doctor before choosing a bed.
The look of any piece of furniture is also important. Some people prefer the softer, more traditional look of wooden beds and others like the sharp lines of ultra-modern metal piping frames. Others will opt for simplicity and just go for a divan model without a visible frame or a headboard. Think about your other furniture before deciding, as the bed is a large piece of furniture and will have a significant impact on the way the room looks. It should match or at least not clash with your existing wardrobe and side table, for example.