I’ve written before about two of the great starter themes — _s (underscores.me) and _tk (themekraft.com). Each wants you to modify the theme to your heart’s content, even to the point of advising you not to use it as the parent for a child theme. _s makes this particularly easy.
Even so, theme development is rarely a linear process; there’s often lots of back and forth. You find yourself realizing you should left in something you deleted, for example.
If you’re modifying the starter theme files, this means going to your backup of the theme file and restoring the bits you need. It’s a hassle.
As an alternative, why not use a starter theme as a parent — at least for development?
The catch is that you need to be able to compare two folders (parent and child, but maybe you guessed that already) to see what’s changed in which files.
If you use an editor such as BBEdit, this is trivial. There are plenty of other comparison utilities out there, though.
The beauty of this approach is that once you have your site looking exactly the way you want it, you compare the two theme folders and merge your child-theme code into your parent-theme code, leaving you with one theme folder that’s perfect, at least for the time being.
This way, you get the best of both worlds. Just don’t forget to save an unedited copy of the version of the starter theme you used, just in case you ever need quickly and easily to see what changes you made.