I haven’t used Blocs or Pinegrow in years, so I can’t give you a good comparison.
RapidWeaver is very flexible, you have a lot of choices in weather you use a Framework (Foundation, Foundry, Platform, Source, etc, etc ), a traditional theme, stacks or other built-in plugins.
With all these choices comes an enormous variants in the kind and quality in the code produced.
For example a styled text page with a traditional theme, will produce totally different semantic HTML than the same content produced by a properly laid out Foundation 6 page.