The best hosting for you would allow you to spin up new websites without impacting your cost. You should be able to manage your own server, where you can install and configure new websites, clone sites between staging and live, and take advantage of a private set of server resources you have 100% control of.
You shouldn’t need to upgrade your plan when your hosted websites are successful, without knowing exactly what resources are being used, and by which sites.
You’re perfect for the LWP Hosting Program, where you get a powerful server, anywhere in the world, with the power to host 30-60 websites.