First of all, sorry for my english:
I am also a web designer and, among others, I've tested these three builders:
Elementor was the first builder I ever used. It has a very large community, hence an extensive list of plugin developers and a wide library of pre-made templates. It was good for me until I met Divi, which offers more attractive designs and, in my opinion, a better UI/UX.
Three months after I bought my Divi permanent license, I found Oxygen Builder, which is a class-based builder. It provides a more sophisticated and versatile approach to website creation. However, it's tailored for advanced users; thus, it's a very powerful builder. You can design complex websites, modify code directly, and integrate advanced features. Yet, if you're not an advanced user, you might end up purchasing and installing a lot of plugins.
About a year and a half later, I discovered Breakdance Builder, and I was amazed. Breakdance is inspired by Elementor. In contrast to Oxygen, Breakdance was built with all users in mind, from beginners to advanced users. Despite carrying similar features to Oxygen, such as templates, a header builder, dynamic data, and conditions, Breakdance is more simplified and user-friendly. Out of the box, Breakdance has over 140 premium elements and built-in compatibility with WooCommerce. It also boasts a vibrant community. Some former Elementor users have claimed they reduced plugin usage by at least half. A positive aspect is that you can still use classes and add custom CSS to each element or any custom code. They have built-in integration for Google Maps, reCaptcha, Facebook App ID, ActiveCampaign, Mailchimp, among others. Moreover, as an advanced user, you can create your own elements with an "element builder" and reuse them across all your sites or even sell them.
Speaking of performance, Elementor is the worst. It loads a lot more code and can make your site very slow. Oxygen and Elementor are very focused on performance, allowing you to achieve high performance grades with minimal optimization knowledge. Breakdance and Oxygen have built-in optimization options, and Breakdance also offers more advanced built-in features such as lazy loading for images and the use of local fonts.
Regarding SEO, both Oxygen and Breakdance are way better
In summary, Breakdance is the best choice for all types of users