You have a catchy name and logo for new product, and you want to protect it. You have done your homework and determined the best way to do that is by applying for registration of a trademark. What should you register?
If the product name is unique, I would start there. Registration of a word mark provides protection for use of that mark in any form with the associated products and services. On the other hand, registration of a design provides protection for that design with the associated goods and services.
If the design mark is dominated by the product name, then I would start from the position that registration of the word mark may be sufficient. Design marks like the Nike swoosh do not include the word mark at all, and they deserve registration. Unfortunately, each mark requires a separate application, and payment of another filing fee.
One final twist. You decide that the design mark is important and you want to protect it. Give consideration to whether you need protection of the particular colours. Registration of a black and white version of the mark without making a colour claim will afford you protection of the design mark in any colour scheme.