I would recommend using a store builder if the purpose of your website is primarily ecommerce. If your website has several purposes— for example you need a blog, photo galleries and also a store— then I would recommend using a website builder. Store builders don't typically have a drag and drop interface.
If you use a website builder for ecommerce make sure that they support full ecommerce. Some website builders advertise that you can build a store— but really only offer "Pay Now With Paypal" buttons. That's not full ecommerce. Full ecommerce has on-site checkout, email receipt customization and more. You can check my reviews of website builders to find out if they support full ecommerce.