I have been using Shopify which serves as online store platform, POS and merchant services for about 2 years. They are stupendous. Their customer service is almost always excellent and available 24/7. They spawned a whole ecosystem of apps that will allow you to do innumerable functionalities to add features on the cheap. Mailchimp, popups, Instagram, etc etc. They blend seamlessly with fulfillment services and even Amazon. Very user friendly: I have no programming background.
Here is the reason you want Shopify: they are the industry incumbent and all the good programmers want to build their app around that platform. That and their excellent customer service - they are always enthusiastically offering new app/plug in ideas to me to solve problems.