web site architecture other than wordpress

I am planning to start a business of building websites for small business firms (support for uploading photos, price listing and support for integrating e-comm support for those who needed). I had a look at wordpress but i think it will be better to look at other alternatives.

I want to use a generic template (with minimal customization (UI alone)t as per customer requirements) to reduce the development and maintenance cost. At the same time I want to have these individual sites as independent as possible. What is the best framework/architecture I can use here? Is it AWS going to be cost effective for this?

thanks, raj