Best eCommerca CMS

What free eCommerce CMS that takes crypto payments do you guys recommend?

Woocommerce, OpenCart, Magento ect.

Also is there a low cost or free way to get SSL Certificate rather then forking up big bucks to Verisign?

i use shopify to sell boating covers and i set up my payments i take btc LTC and others using coin base merchant processor. it was easy to set up and its very user friendly. you can try it on my site to see the user experince. and here is the link to the coinbase commerce hope this helps you. Cheers