This has been a long article but I’m sure I have missed out some aspects that I could have considered. Hopefully, I have demonstrated that although the three themes I’ve discussed are not particularly pretty straight out of the box, they can all be used to build websites with highly customised designs.
My top recommendation is GeneratePress, mainly because of the helpful, sensible and hard-working attitude of its developer, Tom Usborne. Tom released GeneratePress four years ago and has a track record of continuing development and excellent support.
The Astra team also has a good reputation, and I can understand why. Astra was launched a year ago by Brainstorm Force, the developers of the Ultimate Addons for Beaver Builder and Ultimate Addons for Elementor plugins.
While the free versions of GeneratePress and Astra are good, solid themes, I’d recommend buying the Premium / Pro versions to get the most from them.
Nicolas, the founder of OceanWP, has packed his free theme and plugin full of features, since its release just over 18 months ago. Extensions can be purchased to add even more functionality to the theme.
Kadence WP also have some interesting themes and plugins which are worth considering.
UPDATE: In my opinion, the WordPress block editor makes it easier to build pages than it was when I originally wrote this article. I personally choose to use the block editor, along with the GeneratePress theme, rather than a page builder plugin.