Hi and welcome to the site.
If there was one CMS that was the best for eCommerce, wouldn't every eCommerce site use it? So the best CMS for a specific eCommerce development is, perhaps (and in no specific order):
The one that requires the least development time and resources to configure and, optionally, modify to meet the user requirements.
The one the developers are most familiar with (so you are not paying them to learn how to use the tools).
The one that has the best documentation and support.
The one that is most reliable.
The one that is easiest to reconfigure when the user requirements change (which they do).
You may have noticed that at least one of these factors cannot be known in advance.