I am no expert in this field in any way, but here are my thoughts:
I do not think there is a "best theme" for all. It all depends on your own requirements and preferences for your project. The approach I've taken is to install and try out different themes. But when you have a page builder, as you do , I do not think the choice of theme is THAT critical. You can adjust your theme with your page builder and plugins to your needs anyway. That said, I would start as clean as possible to avoid clutter and unnecessary code. Also I would be very picky of plugins, and only install what I really need. You will want your website as lightweight, clean and fastloading as possible.
And I certainly agree with
@jexi. Generate Press is a great theme, and take the right approach. Clean theme, no bloat, lightweight. You can customize, add custom code and add only what you need later. That's what I love about it. Very good price on the premium version, and you get 40% on the renewal. Also great support/support forum. And I bet they will have a nice discount on Black Friday, in a week.
Astra is a very popular theme, also lightweight, though not as lightweight as Generate Press. Astra have many users, and a big team behind it, afaik.
You could also check out Blocksy.