The answer depends on what sort of protection you are seeking for your invention. If you wish to secure the functionality of your invention, then you file a utility patent. . A utility patent will grant you exclusive rights to produce and sell a certain article for a given span of time.
If you are looking to protect its appearance, design, ornamental features, etc. then you should go for a design patent. A design patent will grant you exclusive rights to the appearance of your article only.