Magento

… I also like is the fact it’s not aimed at beginners. It’s enterprise level, and while I’m sure we will still get a stream of very similar Magento websites, all based on the default theme, hopefully their mark on the web won’t be anywhere near as ghastly as that of other open source ecommerce solutions. But for established ecommerce businesses looking to take their site to the next level, Magento is by far the best open source product on the market and definitely worthy of your attention!

LimeSharp Blog, 10 Things We Love About Magento