I am currently looking for options to build a new online shopping website similar to maltasupermarket.com

I will be needing a good CMS to manage products and their categories, prices, stocks, images, description and anything related. I don't mind what kind of CMS to use or if PHP, .NET or anything in between, however this should be easy to use without any complications. 

The CMS should also handle weekly promotion banners or popups, but will see about which one to use or even both.

The quotation would need to include also a website design which should be responsive together with a logo for my idea.

I also want to have a good SEO structure so that I can rank as high as possible for searches in google.