Selecting an ecommerce platform is dependent upon a lot of variables. The number of products you're selling, the customization of those products available, the integration requirements, and the resources for enhancing and improving the platform all play a role. Magento has exploded as the enterprise ecommerce platform of choice because of its flexibility for customization and the huge audience of users developing solutions for and supporting it. We have a Magento Platinum partner we work with, Verge Commerce, who take care of everything from migration, implementation, optimization and even fulfillment.
This infographic from CSS Chopper provides all the insight into the platform's growth as well as why the ecommerce community is so enamored with the platform.