Shopify Buy Button v. WooCommerce for SEO

I have a service-based SEO client on WordPress. I need to develop and SEO their ecommerce branch. Shopify is mainly used by competition (the whole CMS not just buy button) , and the Buy Button seems to have a very slick front and back end interface. Any SEO, development, or scalability limitations when rolling it out this way? Would you suggest a WordPress plugin like WooCommerce instead?