One click ‘select’ and ‘continue’

During a subscription process; the user has to select a product, out of a possible four, and then advance to the next stage where they enter their payment details.

Is there a preference over having the four product buttons also perform the action of moving the user to the next page once clicked or having the product buttons simply to select the product and then a 'next' button to advance.

My preference is to have a "next" button so that each click is performing a single, expected, action. This also allows a default product to be selected upon initial visit to that page.

Alongside potentially reducing clicks, are there any benefits to having the product select button also act as a 'next' button and take the user to the next page?