With 11,729,225 downloads WooCommerce powers over 30% of all online stores. In the UK it is our favourite platform now (see 2015 chart below).
Woocommerce is built on WordPress and offers a seamless store/shop experience with all areas of your site administered from a central panel. Using a mix of Multi-site and WordPress Multi-language extensions, you can quickly set up a store to sell across borders with options to have multi-warehousing and payment gateways to suit your business.
We like using Woocommerce due to a mixture or great documentation, huge open source community, endless connectivity (webhooks, Rest API, Custom Ajax endpoints) and simple migration from your old platform.