My very straight answer would be WordPress all the way! I’ll tell you why and I will also tell you when you can use Wix. Please note that I will refer to Wix, but it would also apply for Squarespace too.
Why not Wix?
Don’t get me wrong, Wix might be a good option for your business. It is effortless to use, has lots of preset templates which would make the build of your business’ home painless.
What I find with these sort of platforms, is that they are not flexible, you have to adapt your design, branding and functionalities to what it’s available. Meaning that if one day you need a special feature, say that you want a quote calculator or integrations with other solutions, you will bump with Wix’s limitations.
My biggest worry with Wix is that you don’t own your website, in the sense that it’s hosted and built by their own system, if the company closes you could potentially lose your site. It’s unlikely.
So WordPress is better?
Short answer, yes.
You can download WordPress at wordpress.org for free.
Note: Using the blog platform (wordpress.com) is not as flexible.
WordPress is an OpenSource with a massive community of developers that keep updating, which makes it quite secure.
WordPress is a bit more challenging to learn than Wix, but it is still quite easy to learn, and because of its popularity you can find thousands of tutorials that can help you from installation to launch.
What I really like about WordPress is that you own it, if you want to move hosting supplier you can do so pretty easily. And can modify it pretty much to do anything you need. Sometimes is challenging to do complicated stuff, but there are lots of developers out there that can help.
Most of the WordPress themes are responsive, which means that they adapt to mobiles and tablets. This is an important feature to have these days because we access a website on different devices.
Finally, WordPress is SEO friendly (Google loves it!), the way is coded it helps to rank to search engines (there is more to SEO than just the platform that is built).
If you are looking for a quick and easy website builder, Wix could be your solution. However, if you are after a future-proof website, where you can build upon and add extensions and more complex functionalities I very much recommend to spend more time and learn WordPress.