Radiators come in various forms. The North American staple of radiators is the finned tube baseboard radiator. Common manufacturers are Slant Fin and Haydon. These are high temperature, high output heaters, with a lot of the heat being provided by natural convection.
European style radiators come in various shapes and designs and are typically lower temperature products, so they require much larger surface area to provide the same amount of heat. The radiators are stylish and durable though tend to be substantially more expensive than other products.
Old style cast iron radiators are still available though usually in the used marketplace. New versions of these radiators are available however due to their weight and physical size, shipping costs are quite prohibitive. These radiators are extremely durable and provide wonderful even heat. They have a fantastic aesthetic appeal, particularly in older homes.
For hard to heat areas, fan coil units are available that can mount on a wall or hide under the kick-space of a cabinet.
Hot water (hydronic) heating is one of the most comfortable and most efficient ways of heating a home. Just ask most Europeans – the majority of homes in Europe are heated with centrally heated water systems.