Wow, plenty of boisterous support for magento here. But really? I'll just list a few and those interested may search on em~
Magento
Opencart
CrystalCommerce
BusinessCatalyst
XCart
Shopify
Tictail
I understand my list is exhaustive, but there really are a ton of ecomerce platforms out there waiting to be discovered and I'm just naming a few off the top of my head!