For a serious online store, WooCommerce; for a simple site with a few products, Wix can be enough.
Wix is a hosted website builder – fast to start, drag-and-drop, everything managed for you. That simplicity is also its ceiling: limited ecommerce features, no real ownership of your data, weaker performance controls, and it’s painful to migrate off once you outgrow it.
WooCommerce is a full ecommerce platform on WordPress. It takes more to set up and run, but there’s effectively no ceiling – complex catalogues, custom checkout, any integration, and full ownership of your store and data.
The rule of thumb: if ecommerce is a small part of what you do and you want the least effort, Wix is fine. If the store is the business – or will be – start on WooCommerce so you’re not forced to replatform later.