I am looking into the best way to make a WordPress theme. The goal is to quickly have a good workflow with professional results, so I choose to build upon an established starter theme.
The first requirements is that it is open source, and battle proven. A simple way to find candidates is to look through the most starred wordpress github projects. This will only return mainstream/popular starter theme, so I might miss interesting narrower themes. The candidates are: WordPress default theme, sage, _s, bones, FoundationPress, wp-svbtle, wordpress-bootstrap, Frank, Wordless, skeleton_wp, HTML5-Reset-Wordpress-Theme, reverie
When looking at the themes, I realise that I would also like tooling built into the theme (as I am not writing enough php to have tuned my own toolbox in that area). Most of the themes looks good, but Sage and FoundationPress looks like the best options, as they both have modern tooling, builds upon established frameworks, good coding style practise, etc.
The major difference seems to be whether you want to build on Bootstrap or Foundation as css framework, which makes me choose to look into FoundationPress.
The small differences in the frameworks, is also similar to the Bootstrap/Foundation difference. Sage(Bootstrap) feels slightly more developer oriented, both with the code structure, and the entire roots deploy framework etc., similar to the way that Bootstrap is popular for quick prototyping for developers. FoundationPress(Foundation), feels very slightly more designer oriented, with more resources for getting started, similar to the way that Foundation solutions do not have the same tendency to have af Foundation-look in the same way that Bootstrap solutions often have a Bootstrap-look.