The verdict
If you are a creator or small brand with no developer, and you want to sell digital products quickly, I'd pick Sellfy. If your site already runs on WordPress, your content and SEO live there, and you have a developer or a trusted agency, I'd pick WooCommerce. The core being free is not the full picture. Hosting, extensions, payment processing and developer time add up, and each extension has its own update cycle. Sellfy's cost sits in plans set by annual sales volume. There is no single winner here. Choose by who will own the maintenance.