Online website builder

I am looking to create a website where people can go inside internally and create and edit a website. Same an [login to view URL] and [login to view URL] They should be able to use different templates, colors, fonts, images, embedd HTML and widgets for social networks. Websites should be professional as well. Also want to be able to upload custom templates as well and be able to edit on the back end. I guess using wordpress will be best for this option. I would also like to have a payment system where they can pay online monthly to use the website builder.