Should I go for utility patent drawings or design patent drawings?

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.