We are the leading osCommerce Partner in the USA. We recommend osCommerce for businesses needing to develop highly customized eCommerce sites. In our experience, osCommerce has the lowest cost of ownership of any open source solution and therefore cost-effective when it comes to the kind of customization required for non-traditional eCommerce workflow.
We recommend Phoenix Cart for simple osCommerce Legacy sites that wish to continue using this code base while taking advantage of its responsive design and improved Add On management that no longer effects the core, allowing for easier core upgrades.
WooCommerce as an eCommerce solution for small businesses that have a story to tell before they sell. Although there are several WordPress eCommerce Plugins available, we prefer WooCommerce given its wide usage.