The majority of radiators on the market are filled with a liquid – namely oil filled radiators or those that work with water. The more liquid in a radiator, the more it will heat. It will therefore be better to select a model with a larger liquid content. These do take a little longer to heat up, but your room will be warmer.
If you are buying a new radiator simply because the old radiator looks old and worn but works fine, think again. An old radiator can be spruced up very nice with a fresh coat of paint; but you must be sure to use specialty radiator paint. See here for more details.
If you are shopping for a new radiator you’re probably focusing on the cost of the appliance and what it looks like. However, what you really need to think about how efficient it will be, and make sure it will heat your home well, without overheating.
The surface area of a radiator determines how much heat it will provide. So in other words, the larger the radiator, the more heat it will give out. Some manufacturers design their radiators to have one panel in front of another, meaning the service area is large while the appliance will not take up too much space, so this is something to look out for. Usually when buying a radiator whether in a store or online, the surface area is stated clearly.
Just like with all sorts of home appliances, some brands tend to be more efficient than others. Look out for a well-known brand such as Dimplex when buying a radiator, as this brand is well-known being high quality.