One fourth category to consider is "quick wins" (papercuts). The smallest things you can do that make customers feel delighted. Not everything will be game changing. These are the items that are easy to build, and still provide minimal value. These often don't qualify as "features", but do make life easier. For example, a simple "copy url" button or keyboard shortcut might fall into this category.

Good example from the Github Team: https://github.blog/2018-08-28-announcing-paper-cuts/