The Choice of Theme for Your Site
Small Sites
When I first discovered WonderCMS I looked through the range of themes and got the impression that WonderCMS was conceived with fairly small sites in mind. I say this on the basis that the first three default themes, "Old Default", "Default" and "Essence", all still available to install, as well as the current default theme "Sky", aren't really designed to allow for more than five or six options to the main navigation menu and all lack the ability to produce neatly presented sub-menus. Of course a site may grow to have a lot of content without the need for a large menu structure. A blog is an obvious example and there is a plug-in available to serve that need. A good number of what might be considered a second group are little more than derivatives of the default themes, with differing colour schemes.
Specialist Markets
The bulk of the remainder, mainly produced by external contributors, are technically more advanced. These often appear to be designed for a particular niche topic or subject area and will not be suitable for most users without significant customisation. Because of the tools used by some of the authors of these themes, such as Font Awesome and Bootstrap, customisation to suit another market may require a fairly advanced level of technical knowledge, beyond the scope of a small business owner, who has insufficient time to learn skills beyond those of their own business area.
An Expandable General Purpose Site
When I found WonderCMS I was hoping to use it for a site that might grow quite large and would need a multi-level menu system. I was unable to find a theme that could deliver that. That's why I began developing my own. I wanted others to find it useful as well so I made it as bland as possible but easy for those with only a very basic understanding of just HTML to be able to add "branding" that made the site distinctly theirs and to present their content in a variety of ways. I explain a little about what's needed on the Web Design page.
To help users my plan was to provide the best possible documentation, so users with no special knowledge would be able to change such things as the colour scheme and practice with sample images to see how to add branding to the site header. The documentation also includes lots of information on how to take advantage of some of the styling built into the theme, so users can do such things as place images, with or without captions, that could appear to left or right but would display full width on phone screens.
If you're looking for a theme that can offer this then It's time to read about the GregCustom theme.