It is generally known that the best type of towel rail is an aluminium towel rail. This is due to it being a more energy efficient solution than mild steel. However, it is a more expensive option to install. By opting for a stainless steel towel rail, you can get an effective solution, for less a smaller upfront cost. Additionally, it is highly energy efficient, this means that your energy bills will be lower, without compromising on an efficient appliance.
With all of these things considered, the best option is for certain, a stainless steel towel rail.