Both are natural, but imperative is simply more commonly used. When applied, this commit will <refactor abc controller>. This commit <refactors abc controller

Both are natural, but imperative is simply more commonly used. When applied, this commit will <refactor abc controller>. This commit <refactors abc controller>. I personally prefer imperative because when you look at a commit it hasn't necessarily been applied yet. But it's like arguing about the difference of potato and potato. As long as you're consistent (and write good messages in whatever style) it doesn't really matter.