Hello there
Normally cms and shopping carts are ready made which they make the job cheaper to develop. However if you don't a ready made solution then I am proposing the best framework for web development. Symfony is my choice for the framework for your commerce application. I will use symfony with bootstrap front end framework for mobile first responsive design. I will also use the library payum to collect payement through the gateway of your choice.
I have over 10 years experience in php and web development looking forward to your response