Though Magento / Zencart are suitable for E-Commerce site set-up , as a Freelancer I prefer going with Wordpress + Woocommerce or WpCommerce or e-Shop plugins with customization. Because you have lot of community support & can find good qualified programmers to help you incase of customization or troubleshooting. Also the framework is bit easier when compared to other frameworks like Magento / zencart. If you have little knowledge in HTML/CSS/PHP , you could do minor tweaks. Also in terms of resource consumption , I admit that WP uses more CPU , but if its properly configured & fine tuned , you can make it work better in performance. Use minimal plugins & delete / remove unwanted plugins even though they are de-activated in the WP admin , as they tend to check everytime whether the plugin is activated or not. Hope this helps.
Really, Magento provides a great platform for E-commerce sites. Because of it's rich pool of plugins, it becomes easy to add new functionality on your site.