Storefront of course. It’s one of those themes that is really useful to work with, especially if you’d like to know more about building or changing a theme yourself. There are paid plugins available that expand the functionality. I also gave examples of working with Storefront in my new book at Packt Publishing:
Socute is a free theme with a premium look and feel. And indeed, also in this case there’s a premium version available. Not that on the download page it seems not to exist, but there’s a button leading you to the free version. Developers Yith are also known for their WooCommerce plugins, which have free versions as well.
In premium themes often page builders are included for complete control over the lay-out of your pages. But in a free theme I haven’t seen that yet. The vantage theme comes in a paid and free version, but even the free version contains the page builder.Download Vantage