Yes WordPress is free and open source but thats not the reason I recommend it. With the largest developer community in the world, WordPress shines as the website publishing platform that can do it all. Whatever your mind can conceive their will be a plugin for that, which saves you time and money on costly developers.
Having a reliable website hosting company is one of the most important decisions you will make when starting an online business. WPX Hosting is what I use because they use lightning fast servers designed to work best with the next app on this list WordPress. They also have amazing support and nothing is ever too much trouble for them to fix even if it was your own fault your website blew up. Yes it happens and its good to know you have WPX on your side when it does.
Elementor is a page builder for WordPress that gives you the exact design tool to make WordPress look like a professionally designed website. You will find no ugly blog layouts on your website when using Elementor (free version here) and Pro version has unique features that allow you to build entire websites without using a dedicated theme. This makes your website faster and gives you full control over the entire layout of your website and not just what the theme designer allows you to edit.
As your website popularity grows, you may want a membership system to provide your fans with exclusive content. When that time comes Member Mouse should be high on your list to install. It gives you a lot of flexibility to create products and membership levels to protect any content you choose. It also integrates with PayPal, Stripe and other payment gateways.
This plugin comes to you from Automattic who are the people behind WordPress so you can be confident knowing that this is the app to use when selling products from a WordPress website. Best of all you can get all the core functions you need as part of the free version.