Structure B
Keep content and assets together.
Pros
- Content files and corresponding assets are in one folder. This is very clean
 from a content perspective since I consider images of a blog post also as
 content (not processd, but still content). For example, we can create a zip
 file from a blog post folder with markdown and images and we have everything
 that belongs to that blog post.
- Images in the content folder are also much easier to maintain.
 For example, if we delete a blog post, we can savely delete the blog posts
 images as they live in the same folder.
- References to images are short (for example post-image-1.jpg). This also
 means that Github finds and displays the images when the markdown file is opened.
Cons
- Content contains a mix of files to be processed (markdown) and static files
 (images). If we did some image optimization/resizing/cropping, we could argue
 that images are processed as well and thus belong to the content folder.
- A lot of folders to manage in the content directory (comment by @alexandros).
CONTENT
Includes images and possibly other assets.
├── content/
    └── _index.md
    └── home-image.jpg
    └── about/
    │   └── _index.md
    └── blog/
        ├── _index.md
        ├── firstpost/
        │   └── index.md
        │   └── post-image-1.jpg
        └── secondpost/
            └── index.md
            └── post-image-2.jpg
LAYOUTS
├── layouts/
    └── index.html
    └── about/
    │   └── list.html
    └── blog/
        ├── list.html
        └── single.html
STATIC SOURCE FILES (OPTIONAL)
This folder is ignored by Hugo. It is only used for preprocessors to generate files
into the static folder.
├── static-src/
    └── sass/
    │   └── style.scss
    └── js/
        └── main.js
STATIC
├── static/
    └── favicon.ico
    └── images/    // (only globally used images)
    │   └── logo.png
    └── css/
    │   └── style.min.css
    └── js/
        └── main.min.js
PUBLIC (generated files)
├── public/
    └── index.html
    └── favicon.ico
    └── home-image.jpg
    └── images/
    │   └── logo.png
    └── about/
    │   └── index.html
    └── blog/
        ├── index.html
        ├── firstpost/
        │   └── index.html
        │   └── post-image-1.jpg
        └── secondpost/
            └── index.html
            └── post-image-2.jpg